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Llansadwrn (Anglesey) Weather
Monthly summary for 2001

Logo: Llansadwrn Weather - Melin Llynnon, Ynys Môn



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January 2001

Dry and sunny below average wind. Below average temperatures.

After the wet autumn, and year of 2000, January 2001 started wet with 18.7 mm in the first 3 days but then turned dry. With 44.0 mm (44% of ave) it was the driest January since 1997 that had only 6.6 mm (driest on record). Before then the driest was in 1987 (26.7 mm). There have been only 6 drier Januarys in records back to 1928. There were 12 dry days (+8.8) and only 14 (-4.6C) rain days (0.2 mm or more). Number of wet days (1.0 mm or more) was 11 (-3.6) and there were only 2 days (-4.4) with 5 mm or more. The wettest day was on the 3rd with 10.4 mm

Temperatures were below average. The mean of 4.2C (-1.1) was the coldest since 1997 (3.9C). The highest mean of 8.1C was on the 3rd while the lowest of 0.8C was on the 16th. The mean maximum of 6.9C (-0.9C) was the coldest since 1991 (6.6C) and was the 7th coldest on record since 1979. The highest maximum of 10.6C was on the 1st while the lowest of 4.1C was on the 16th. The mean minimum of 1.4C (-1.3) was the coldest since 1997 (0.7C) and was the 6th coldest since 1979. The lowest minimum was -2.6C on the 17th, well above the lowest in the last 10y of -6.2C and the absolute lowest -7.5C in 1987, while the highest 7.3C was on the 2nd. The mean minimum was near the mean monthly lowest average of -2.8C but the maximum was well below the mean monthly highest average of 12.0C. There were 10 air frosts (+4.1) and 20 ground frosts (+5.3) being the most since 1997 (25).

There were 2 windy spells in the month. The first at the beginning with fresh to strong S-W on 1st and 3rd; and the second, fresh E'ly winds on the 11-12th. Otherwise winds were light; there were 9 days on which it was calm during the 0900 GMT observations and there were no gales.

Cloud cover at 0900 GMT averaged 58% which was low for January. Several days were cloudless or nearly cloudless including 13-17th. On the 14th I noted the sunrise and sunset times and this gave the day's sunshine as 7.5h. There were 6 sunless days. Valley reported 93.6h sunshine for the month (153% of average). Sunniest day was the 14th with 7.0h. In contrast at Abergwyngregin (Gwynedd) there were only 71.5h (12 sunless days) but this was 200% of average.

Sleet, 5 mm hail and ice pellets fell on the 20th and was the only day to have this type of precipitation. No thunder was heard during the month.

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February 2001

Wet and mild start; dry and cold end.

February began rather wet with 100 mm in the first 11 days (113%; 135% LTA). Temperatures in the first half were a little above average with a mean of 5.8C (+0.2); in the second half they were well below average with a mean 4.1C (-1.5). There were few airfrosts (4) but again there is a distribution of 1 in the first half and 3 in the second. Ground frosts were more equally divided with 6 in the first and 11 in the second half of the month.

The end of the month (23-28th) brought sleet and snow (5 days, including 1 on which snow pellets fell) and numerous showers of snow pellets (3 days) and ice pellets (3 days). Snow was lying (2 cm) on the morning of the 28th. Later in the day there was a moderate fall of conical snow pellets that included some as large as 9 mm diameter x 6.5 mm high.

February 2001 

                Rain          Air temp (C)
       Days     (mm)      Max      Min     Mean       AF       GF

      01-14    100.2      8.6      3.0      5.8        1        6
      14-28     13.7      6.9      1.2      4.1        3       11

     Month     113.9      7.8      2.1      5.0        4       17

For the month as a whole the mean of 5.0C (-0.6C) was the coldest February since 1996 (-4.0C) and was the 11th coldest on 23y records. The mean maximum of 7.8C was also the coldest since 1996 (6.7C); there have been 6 colder Februarys. The highest maximum of 10.8C on the 14th was the coldest since 1994 (10.4C) and is the third coldest overall. The mean minimum of 2.1C was the coldest since 1996 (0.6C) and was the 10th coldest overall. The absolute minimum of -1.6C on the 9th (in the warmer part of the month) was again the coldest since 1996 (-4.0C) but only the 13th coldest overall. There were 24.6 h of airfrost. The lowest grass minimum of -6.0C (-1.0) on the 18th, lowest since 1997, but not as low as my record low of -11.0C 1985.

Total rainfall for the month was 113.9 mm (129%; 154% LTA). This was not as wet as February 2000 that had 143 mm but there have been only 13 wetter since 1928. There were 6 dry days (-1.5) and 20 rain days (0.2 mm or more). Wet days (1.0 mm or more) numbered 16 (+2.4) while there were 8 days (+1.6) with 5 mm or more. Rainfall duration was 97.4h.

There were only 2 windy spells in the month. On the 6th the wind reached gale force, 2 lorries were overturned on the A55 Expressway, and several Irish Sea ferry sailings were cancelled. Valley reported gusts of 60 mph. On the 27th the strong NE'ly winds did not reach gale force but the average wind speed over the 24-h was greater (13.5 mph compared with 11.5 mph).

The period 19-22nd was unusually foggy. The days were misty with poor or very poor visibility becoming foggy at night, often thick fog (<100m). On no days was fog recorded at 0900 GMT!

Cloud cover at 0900 GMT averaged 6.5 oktas (82%). Cover was evenly distributed throughout the month (days 1-14 6.4 oktas, 14-28 6.6 oktas). Sunniest days were the 8-9, 16 and 24th. The sunniest was the 14th when Valley reported 8.2h; there were 4 sunless days. In all Valley reported 83.4h sunshine (136%).

No thunder was heard during the month.

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March 2001

Dry and sunny with below average temperatures

It was a dry month with only 35.0 mm (41%; 49%LTA) and the driest March since 1993 that had 27.0 mm There are only 10 other drier in records since 1928 in which the driest was 1990 (18.3 mm). Also it is the driest of ANY month since July 1999 (26.1 mm); May 1998 (25.3 mm); April 1997 (30.8 mm) and Jan 1997 (6.6 mm) the lowest on record. There were 11 dry days ( with a spell of 5 days between 1-5th) but there were 16 raindays (-1.6) and 12 wetdays (-0.5). There was only 1 fall of 5 mm, or more, on the 31st (5.9 mm) that was the wettest day in the month! The month's rainfall can be summed up as 'little but often'. With mainly E'ly airflows this part of the island often benefited being in a rain shadow area. On the 21st, rainfall here in the lee of the Snowdonia Mountains was only 3.6 mm, but at Valley 25 km W it was 10.4 mm Valley's total for the month was 45.4 mm

Temperatures were below the average for March with the mean 5.9C (-1.3). Lowest mean 0.6C was on the 3rd within a cold spell 2-4th that had means below 1C. There were only 2 days with a mean >10C; 10.7C on the 8th and 10.3C on the 31st. Minimum temperatures were also quite low in this spell with -4.1C (2nd), -4.5C (3rd) and -5.0C (4th) the lowest of the month and coldest in March since 1986 (-5.2C). There were 6 airfrosts, the most since the 9 of 1987. The grass minimum of -10.2 on the 4th was the lowest in March in records since 1985. My lowest grass minimum was the -11.3C recorded on 30th December 1985. There were 14 ground frosts, the most since the 15 in 1995 and 1985. The mean maximum temperature was 9.3C (-0.8). In a milder spell 6-14th 13.5C was recorded on the 8th, the highest of the month. There were some other mild days towards the end of the month with 11.8C on the 23rd and 12.5C on the 24th. The last day, the 31st, nearly became the warmest day when the maximum reached 14.0C. Although the month ended with a mean maximum below average there were 14 days that reached 10C or more.

Evaporation (PE) measured by lysimeter increased during the month, positive values (total 12.8mm) being recorded for the first month since October. Piche evaporation values also increased (35.1 mls).

Cloud cover at 0900 GMT averaged 5.3 oktas (67%) and there were some good sunny days. The 3rd, 4th, 13th and 14th all had 10, or more, hours of sunshine. A further 4 days had more than 9 hours. Valley reported a total of 159.6h (137%) in the month and there were only 4 sunless days.

Wind direction was mainly in the NE-S sector (20 days) with only 7 days SW-W. There were 2 days with N'ly wind and 2 of calm. This was important in the distribution of the foot-and-mouth virus that can be airborne as, so far, confirmed cases have been confined to the SW corner of the island. Go here for an analysis. There was only 1 windy spell on the 20-21st with E'ly winds in excess of force 6. During the morning of the 20th a tree fell onto the railway line at Abergwyngregyn, damaged a train and closed the line for several hours. The wind locally reached gale force 8 after midnight on the 20/21st. During strong gusts of wind and downdraughts from the Snowdonia Mountains several trees were brought down in Bangor where several roads near the University were closed for a time. Here, a sycamore tree was brought down across the road during the night.

Days with hail (2) were a little below average (-0.7). Ice pellets fell on the 13th while snow grains fell frequently on the 21st. On the 1st large snow pellets, that fell on the 28th February, were still lying on the ground at 0900 GMT on the 1st being recorded as snow (ice) lying. Snow and snow flurries occurred on the 17th, 18th and 21st. There was no thunder heard during the month.

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April 2001

Wet and rather cold

With 103.8 mm rain (140%) it was the wettest April since 1994 (127.1 mm) and the 6th wettest in records since 1928. While only 140% of the 10y average it was wetter when compared to the LTA (169%) and 1971-2000 (180%). There were no exceptional falls, the largest being 14.4 mm on the 5th followed by 12.7 mm on the 6th. Days with 5 mm, or more, were 9 (+4.0) while raindays (0.2 mm, or more) were 19 (+2.0) and wet days (1.0 mm, or more) 17 (+3.8). There were only 4 dry days in the month.

Temperatures continued to be below average, the 4th month in succession this year. The mean was 7.7C (-1.0) was the coldest April since 1994 that had the same value and, in records since 1979, are joint coldest to the 6.8C mean in 1986. There were only 2 days, the 1st and 2nd, that had means above 10C. The mean maximum of 11.0C (-1.3) was the same as 2000 and the coolest since 10.7C in 1986. There were 7 days with maximums below 10C with the 22nd having only 7.0C. Minimum temperatures were also below average with the mean of 4.4C (-0.7C) warmer than the coldest (2.4C) in 1995/96. There were, however, no airfrosts but there were 11 ground frosts (+5.7). The lowest (3.0C on the 21st was only 0.1C below the average.

With warmer air and soil temperatures evaporation measured by lysimeter totalled 24.7 mm There was a potential water balance of 79.1 mm and the soil remained near saturation most of the month with water standing on the morning of the 29th.

Wind direction became more normal with 21 days in the S-NW sector. There were no gales and no calms recorded at 0900 GMT.

Sleet or snowflakes were seen on 3 days while snow pellets occurred on 2 days. Ice pellets fell on the 4th and 28th. There was no thunder heard during the month.

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May 2001

Drier and warmer than average

Mean temperature graph for May 2001

The month ended drier than average (74%) with 48.7 mm making it the 26th driest in records since 1928. If it were not for 2 large falls, 10.6 mm on the 14th and 16.3 mm on the 27th, it would have been one of the driest. The driest May, with 19.0 mm, was recorded at Treffos in 1939, but it is only necessary to look back to 1998 to see 25.3 mm during the driest 12- and 24- month period on record. There were 17 dry days (+3.5) and only 12 rain days (0.2 mm or more); 8 wet days (1.0 mm or more) and 3 days with 5 mm or more.

For the first month this year mean temperatures were above average. The daily mean was 12.4C (+0.7) while the mean maximum was 16.3C (+0.6) and the mean minimum 8.4C (+0.8). There were 2 warm spells: the 3-day spell 11-17th all had maximums of 20C, or more, the highest being 23.7C on the 12th; and the 5-day spell 21-25th with 3 days of 20C, or more, with the 24th having a maximum of 24.0C, the highest of the month. The coldest part of the month was at the beginning 1-7th with the lowest minimum of 3.5C on the 5th that also had the only ground frost of the month (-0.2C). Between the 2 warm spells there was another colder spell from 14-19th with a minimum of 4.3C on the 18th when the temperature above the grass dropped to 0.8C. There was no airfrost.

It was a sunny month with cloud cover at 0900 GMT an average 5.2 oktas or 65%. Valley (Anglesey) reported 255h of sunshine which was above the average but much less than last May that had 286h. The sunniest days were 11-13th and 21-25th.

Winds throughout the month were generally light and spread around the compass at 0900 GMT; N-SE (16 days) S-NW (14 days) and 1 calm. It was windiest between 28-30th. On the 28th the SW'ly was near gale force for a time in the afternoon with some strong gusts that brought down twigs and leaves from many of the trees in the area. There were no gales in the month.

Soil temperatures reflected the air temperatures and were above average. At 30 cm the monthly mean was 13.8C (+0.6). The lowest was 10.6C on the first and the highest 16.5C on the 25th. Evaporation measured by lysimeter was 58.9 mm in the month. This gave a negative potential water balance of -10.2 mm. The surface soil on the bare plot was dry on 7 mornings but there was plenty of water in the soil for plant growth and irrigation was unnecessary.

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June 2001

Dry with near average temperatures and sunshine

For the 2nd month in succession and the 4th this year rainfall with 30.3 mm (41%) was below average. It was the driest June since 1988 (19.8 mm) and 1976 (29.7 mm) and was the 11th driest in records here since 1929. There were 14 dry days (+2.3) while there were 10 days (-5.5) on which rain fell amounting to 0.2 mm or more. There were only 6 wet days (-4.4) of 1.0 mm or more and 2 with 5 mm or more (-2.6). The wettest day was on the 14th with 14.1 mm.

Temperatures were near average with the mean of 13.4C having an anomaly of just -0.2C. The mean maximum of 17.0C was just -0.3C and the mean minimum of 9.8C on the average. The highest maximum was on the 26th with 25.8C; there were only 4 days with 20C or more. The lowest maximum of 12.6C was on the 6th. The lowest temperature were on the 8th with a minimum of 3.5C and grass minimum of 0.9C. Both of these were the lowest in June since 1991 when there was a minimum of 2.0C and 0.1C above the grass. Since temperature records began here in 1979 there has never been a June frost.

Mean soil temperature at 30 cm (15.7C) was a little above average (+0.3). The highest was 18.2C on the 27th and the lowest 14.2C on the 8th. The soil surface was recorded as dry on 18 mornings and although evaporation was not unusually high for June (PE 55.3 mm) there was a negative potential water balance over the month of -25.0 mm. This had little or no effect on natural vegetation having deep roots, grass and most crops as there is still plenty of water for plant growth. Some watering had to be done on the vegetable plot; seedlings, lettuce and runner beans at the end of the month.

Sunshine was near average with Valley reporting 213h (10y average 206h). Sunniest day was the 10th with 15.5h. There were no gales in the month with the 29th being the windiest day. There was 1 day with thunder and lightning (26th) but there was little rain associated with it and no hail.

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July 2001

Dry with near average temperatures

Rainfall of 45.9 mm was below average (77%) for the 3rd month in succession. It was the 5th month this year to have below average rainfall with the total for the year standing at 421.6 mm; the driest January-July period since 1996 (369.9 mm) and 1991 (396.7 mm). There were 12 dry days (+0.6) and 15 raindays (0.2 mm or more). The number of wet days (1.0 mm or more) was 10 and a little below average (-0.3) while days with 5 mm or more only 3 (-1.0). The wettest day was on the 3rd with 11.2 mm during the large thunderstorm that affected the Conwy Valley and Llandudno when 67 mm was recorded at Llandudno.

Mean temperature graph for July 2001

Temperatures were near average with the monthly mean of 15.3C (-0.3). There was a cold spell around the middle of the month. On the 15th the minimum fell to 4.1C the lowest in July since 1980 and 1984 that both had 5.6C. This was the 3rd lowest July minimum on record here since 1979. On the same night the temperature above the grass fell to 4.1C. The beginning and end of the month saw mean temperatures up to 4C above average. In a carry over from the warm spell at the end of June the 1st had a mean of 18.1C while the 28th had 19.8C. Maximum temperatures were not very high compared with those in the Midlands and the SE where 28-32C were frequently experienced. There were 11 days with 20C or more, 4 at the beginning and 7 at the end of the month. The warmest day was on the 28th with a maximum of 25.9C, the only that to reached more than 25C. As a result the mean maximum of 18.9C was -0.5 of average. The mean minimum of 12.0C was exactly on the average for the month.

Soil temperatures at 30 cm were on the average of 17.2C. The highest seen was 18.8C on the 6-7th and again on the 29-31st. The surface of the soil was recorded as dry on 12 mornings while the grass was dry on only 4 mornings. In the absence of other moisture dew was present on grass on 11 mornings. Evaporation measured by lysimeter was 53.9 mm resulting in a negative water balance for the month of -8.0 mm. Again like June there was little effect on natural vegetation except roadside verges that looked quite yellow by the end of the month. The vegetable plot needed some water on lettuces and runner beans during the month but peas only needed some towards the end of the month to aid swelling of peas in the pods. Broad beans and brassicas have required no water.

There was a large thunder storm on the 3rd centred over the Conwy Valley and Llandudno where there was heavy thunder and lightning and torrential rain. An eyewitness described the lightning as similar to that experienced in the tropics. Here there was heavy thunder and lightning but rainfall was only moderate with 11.2 mm.

On the 17th there were strong E-NEly winds during the afternoon and evening that reached gale force 8 at times after midnight. Much salt spray was blown inland along the North Wales coast from Abergele to Red Wharf Bay on Anglesey. This led, in succeeding days, to noticeable damage to susceptible plants and trees. Some trees along the coast near Colwyn Bay suffered leaf scorching and leaf drop to such an extent that the scene looked more like November than July.

Sunshine was near average for July with Valley reporting 208.6h (104%). It was quite cloudy at times with 4 sunless days. The sunniest day was on the 15th with 12.1h and 8 days had more than 10h.

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August 2001

Rather cloudy, cool and wet

The spell of dry months was broken this month with 96.7 mm of rain (130% of average). It ranked 31st wettest since 1928 but over the summer as a whole rainfall was 172.9 mm that ranked only 55th wettest. It was certainly a drier month than last year that had 132.4 mm. There were 10 dry days (-1.1) but 20 raindays (+5.2). Both wet days 17 and days with 5 mm or more were above average (+6.0 and +2.6 respectively. The wettest day was on the 18th having 14.5 mm but the 15th also had 11.7 mm. Rainfall duration was 74.9h of which 10 h were on the 18th. This was an average of 1.4 mm per hour but on the 4th there were 2 short but heavy showers, from strongly convective clouds, when the average was 16.5 mm per hour but only 3.3 mm rainfall.

Click for graph of maximum temperature anomaly 1979-2001.

Maximum temperatures were on the cool side with the mean 18.7C (-0.8). This was the coolest since 1994 (18.0C). The highest maximum of 24.2C was on the 1st coupled with 20.6C on the 2nd; the second warmest was 22.5C on the 29th coupled with 21.8C on the 28th. In between they were rather mediocre with only the 14th reaching 20.8C. Only 5 days of 20C or more! For the second month this year we did not see any of the high temperatures (28-32C) experienced further inland and S. Maximum temperatures have been near the long-term average for the last 4 years (see graph). The last group of warmer than average Augusts was 1995-97 that included the warmest in 1995 that was +3.8C. But there have been groups of colder Augusts with the greatest anomaly of -3.0C in 1985. Minimum temperatures were average with the mean 12.1C. There were 2 cold nights with 8.5C seen on the 10th and 28th. The mean grass minimum 10.2C was near average (-0.1). The lowest grass minimum was 5.5C on the 27th. The monthly mean of 15.4C was equal with 1999 (15.4C) in being the coolest since 1993 (14.2C).

Soil temperatures at 30 cm were a little above average with the mean 17.4C (+0.2). The soil surface was dry on 4 mornings but the grass was wet every morning either because of rain or dew that was often heavy. Evaporation (PE) measured by lysimeter was only 41.7 mm. and 35.1 mls by Piche evaporimeter. There was a potential water balance of 55.0 mm and no watering of the vegetable plot had to be done. PE was greater than the 33.2 mm seen in 2000 but less than the largest of 73.1 mm in 1997 (5 years of records).

Winds were unusually light through the month. The windiest day was the 21st. There were several days on which the blades of the wind-power generators at the 3 wind farms on the Island were not turning. Not a good month for 'green' power generation!

It was a cloudy month on this part of the island with an average of 6.4 oktas (80%) cover at 0900 GMT. While not as cloudy as April (83%) and June (85%) there were several sunless or almost sunless days. In particular there were 2 spells from 11-13th and 23-25th of persistent low cloud and fog, with relative humidities close to 100%, when it was sunless . Other days were on the 2nd and 7th. There were some good sunny days on the 1st, 5th, 9-10th, 22nd and 28th. Valley reported 185.1 h of sunshine that was 92% of average; sunniest day was on the 28th with 13.0h.

Thunder was heard on the 4th but there was no hail.

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September 2001

Cool with average rainfall

An average month for rainfall (98.2 mm, 98.2%) but was the lowest since 1998 (89.9 mm). There were 3 large falls; 18.0 mm on the 12th over 13.2h the longest (1.4 mm /h), 18.5 mm on the 28th over only 3h (6.2 mm / h) and 19.7 mm over 5.8h (3.4 mm / h) on the 30th. These 3 days were responsible for over half the months total rainfall. There were 21 raindays (+5.8) but wet days 11 and days of 5 mm or more were each below average (-1.9 and -0.6 respectively).

Maximum temperatures were again on the cool side with a mean of 16.1C (-1.2). This was the lowest since 1994 (15.1C) and ranks as the 4th lowest on record since 1979. Only 1 day exceeded 20C, that was on the 28th with 22.4C. The lowest maximum was 13.0C on the 17th. In contrast mean minimum temperatures averaged 10.7C (+0.5) this once again reflecting the number of cloudy cloudy nights. It was the lowest since 1996 (10.0C) but ranked 7th highest on record. The lowest minimum of 8.0C on the 14th was the warmest on record for September. On the same night the grass minimum was 3.0C (+0.3) and shallow fog formed before morning. Shallow fog formed again early on the 21st but soon cleared. The mean grass minimum of 8.2C was close to average.

Soil temperatures have begun to decline with the mean at 30 cm 15.3C (close to the average). Mean temperatures near the surface are now lower than the deeper ones. The progression was 13.7C at 5 cm, 13.8C at 10 cm, 14.6C at 20 cm, 15.3C at 30 cm, 15.6C at 50 cm and 15.3C at 100 cm. Evaporation (PE) measured by lysimeter was 36.3 mm and there was a water balance (PWB) of 61.1 mm.

A much better month for wind-power generators with the first half of the month with moderate to strong. On the 12-13th the SW-W'ly wind was near gale for much of the time. After a quieter spell between 20-26th winds became strong again for the last 4 days with a gale on the 30th.

There were some cloudy days but many had at least some sunshine. The wind was N or NW'ly on 11 days and when this happens it tends to be cloudy on this part of the island whereas the coastal to the W and N remains clear. Cloud cover at 0900 GMT averaged 6.6 oktas (82%). At Valley sunshine was 146h and close to the average of 148h. The sunniest day was on the 4th with 12.1h and there were 3 sunless days and 6 others with 2h or less.

Thunder and lightning occurred in the early hours of the 29th but there was no hail.

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October 2001

Very mild and dry

October was the warmest on record in the UK. My temperature records go back to 1979 and the mean of 13.2C (+2.6) was the warmest but only just beating the 13.1C in 1995. The mean minimum of 10.7C (+3.2) was also the warmest while the mean maximum of 15.8C (+2.1) was second only to 1995 that had 16.0C. It was a very pleasant month and more so as it was only the second month of the year (along with May) with above average temperatures. The highest maximum of 19.3C on the 17th was not exceptional, indeed followed the trend this year for rather low maximums, but was 20.2C at Valley that was the warmest place in the UK on the day. It was the warmest since 1997 (24.0C), but there have been 10 Octobers that have seen temperatures >20C. Minimums have been high with the lowest 6.4C, on the 31st, the warmest on record and clearly beating the previous 5.6C in 1996 the only other above 5C. There were no ground frosts (the average is 3) and the mean of 8.3C was 3.2C above the average; the lowest of 2.3C on the 28th was 3.3C above average. Soil temperatures were above the average with the mean at 30 cm 9.8C (+1.3).

While a lot of places have seen rainfall well above average here it has continued below average. The total was 85.7 mm some 74% of average (72% of the LTA) and 70.2 h duration. It is the 6th month this year with below average rainfall making it one of the driest on record since 1928. The largest fall of 15.6 mm was on the 19th. There was rain (>0.2 mm or more) on 20 days (+0.6) and the number of wet days (1 mm or more) was 18 (+2.1). Both of these were not far from average while the number of days with 5 mm or more was 6 (-1.9). Dry days were 8 again close to the average. It seems that while the days on which it has rained are near average the amount of rainfall has been less than usual.

It was a windy month with most winds from the S (12 days) and SW (9 days) and of strong to gale force on several days. There were gales on 4 days (1st, 6th, 25th and 30th). The beginning og the month (1-12th) and the end 23-31st were particularly windy but there were 2 quieter spells on the 13-14th and 20-23rd. The month was notable for the spectacular lee-wave clouds over the Menai Strait and SE corner of the island including Llansadwrn on the 12th and the remarkably heavy fall of orange coloured Saharan dust on the 14th.

Soil temperatures have been above average with a mean of 13.5C at 30 cm depth 1.8C above average and the warmest on record. Despite the warmth the seasonal decline in soil temperatures has continued with significant differences from September. Temperatures down the profile and their differences from September are 11.9C (-1.8) at 5 cm, 12.3C (-1.5) at 10 cm, 12.9C (-1.7) at 20 cm, 13.5C (-1.8) at 30 cm, 13.9C (-1.7) at 50 cm and 14.0C (-1.3) at 100 cm. Contrast these with air temperatures that are hardly different from September; maximum 15.8C (-0.3) and minimum 10.7C (0.0). Evaporation (PE) measured by the Piche evaporimeter was 43.9 mls larger than both August and September but by lysimeter was only 11.1 mm, less than September. This is most likely due to dew (there were several days with very heavy dew) and lower soil temperatures affecting the lysimeter and windiness that has more effect on the Piche.

Cloudiness (at 0900 GMT) was an average 5.6 oktas or 70% and was the lowest since the 65% seen in May. It was an average month for sunshine at Valley with a reported 117.6h. Sunniest day was the 28th with 8.9h (highest in the UK) and there were 5 sunless days.

There was heavy thunder and lightning in the early hours of the 1st and there were ice pellets with some 5 mm diameter hail during the night of the 31st.

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November 2001

Mild and dry at first

It was another mild month with a mean temperature of 8.3C (+0.6) the warmest November since 1997 (9.2C). It was the 4th warmest in records since 1979 but fell far short of the remarkable November in 1994 that had a mean of 10.1C. The mean maximum of 10.8C (+0.4) ranked 5th warmest with 1994 having 12.4C. The highest maximum was 14.7C this falling on the 2nd and nowhere near the 16.6C recorded at Hawarden (Flintshire) on the 30th, a UK record for that date. The lowest maximum was 6.0C on the 8th that experienced a taste of wintry precipitation. The mean minimum of 5.8C (+0.7) was ranked 3rd warmest against the 7.9C in 1994 and 6.8C in 1997. There were no airfrosts with the lowest minimum of 1.8C on the 26th.

Click for graph of accumulated monthly rainfall

Rainfall on the first 27 days of the month was well below average with a total of 59.7 mm only 48% of the long-term-average. But 31.6 mm fell on the 28th and 15.0 mm on the 29th. By the end of the month the total was 107.7 mm bringing the month up to 83% of average (86% LTA). Until then rainfall for the year had been the driest on record with 8 months having below average rainfall! The total rainfall January-November is 809.9 mm and is still one of the 9 driest periods on record. During the year the accumulated rainfall total month by month has been below that of 1945, the driest on record, on 5 occasions. There were 6 dry days (+1.9) but only 6 days with 5 mm or more (-3.1). There was rain (0.2 mm, or more) on 21 (-1.5) days and there were 16 (-1.4) wet days (1.0 mm, or more).

Mean pressure for the month was 1024 mb, the highest monthly mean of the year, and above the average of 1012 mb. With anticyclonic conditions there was little or no wind on several days calm being recorded on 5 mornings. There was 1 wintry gale on the 8th with a mean wind speed of 13.8 mph over the 24-h period (09-09 GMT).

It was a very poor month for sunshine with Valley reporting only 47.6h (80%). There were 12 sunless days and another 4 had less than 1h. Sunniest day was the 13th with 5.9h. Cloud cover in Llansadwrn at 0900 GMT averaged 86%, the highest of any month in the year.

No thunder was heard but there were 4 days of ice precipitation. On the 8th ice pellets, 7 mm diameter hail were seen during the day. Later in the evening there was sleet and showers of minute snow grains before midnight that carried over to the 9th. Also on the 9th were some snow pellets. Ice pellets were recorded again on the 13th and 27th.

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December 2001

Dry, sunny and frosty

A colder month with a mean temperature of 5.0C (-0.5) making it the colder December since 1996 (3.9C). Maximum temperatures, with a mean of 7.8C were near the average (-0.1), it was the minimum that were below average with a mean of 2.2C (-0.9). The highest maximum of 12.4C was on the 8th while the coldest day with 3.3C waited until the 30th. The highest minimum of 8.1C was on the 1st and the lowest of -1.5C was on the last (31st). There were 8 (+2.4) airfrosts in the month the most in December since 1996 (12). The number of ground frosts (22) was well above the average (+8.3) and tied with 1989 (22) having the most on record. There were 40.9h of frost (recorded autographically in the Stevenson screen).

With 56.1 mm precipitation (rain and melted ice and snow) that was 45% of average, December rang up the 8th month of the year to have below average rain. There were 11 dry days (+6.0) and 18 rain days (-2.4) with 0.2 mm, or more. There was a lack of heavier rain also with 12 wet days (-4.4) having 1.0 mm, or more, while there were only 4 days (-5.0) with 5 mm, or more. It was the driest December since 1996 that had 43.5 mm and ranked the 12th driest on record in Llansadwrn since 1928.

It was a sunny month with cloud cover at 0900 GMT averaging 5.4 oktas or 67%. It was, jointly with March, the 2nd least cloudy month of the year. Several days were particularly sunny (8-14th) with almost cloudless skies, for example the 10th with 7.3h (by observation) compared with Jersey's 7.6h. This in spite of the maximum sunshine being additionally shortened at this time of the year because the sun must first rise above Ysgolion Duon (3185 ft) the col between Carnedd Llywelyn and C. Dafydd on the mainland SE of here. Valley reported 76.9 h sunshine (145% of average) but there were 7 almost sunless days.

Pressure was high for the second month in succession and averaged 1025 mb (+12 mb) just putting November into 2nd place as the highest mean of the year. Again with anticyclonic conditions prevalent wind was moderate for the time of year. Calm was recorded on 8 mornings but there was a gale on the 3rd. Wind directions were interesting as there was only 3 mornings with a S to SW'ly wind while SE to NE'ly there were 8. W to N'ly accounted for 12.

Ice precipitation was seen on 6 days with 5 of them having sleet or snow and 6 some type of hail. The predominant type of hail was snow pellets (formerly soft hail) on 5 of the 6 days while ice pellets (small hail <5 mm diameter) fell on 3 days. On the 25th a moderate fall of snow pellets was followed by spells of snow in the night that led to 6 cm lying ice/snow on the morning of the 26th. There were further showers of ice pellets, snow pellets and snow on the 29/30th that led to 2 cm of lying on the 30th. This was still lying locally to 1 cm on the 31st. There was a remarkable range in size of conical shaped snow pellets seen in the month. On the 23rd they were 1-2 mm while on the 25th, 26th and 29th they were the more normal 2-5 mm diameter ones. On the 30th, however, I found many of them 7-8 mm diameter.

There was no thunder heard in the month although there were cumulonimbus clouds developing in the vicinity on the 30th.

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Annual 2001

Dry but cool

Click for graph of accumulated monthly rainfall

Total rainfall for the year was 866.0 mm 79% of average (81% LTA). It was in complete contrast to 2000 that, with 1483.9 mm was the wettest year on record. For a while it looked as if 2001 was turning out ot be the driest! Only 4 months, February (129%), April (140%), August (130%) and September just (101%) had above average figures. The accumulated monthly total had run below the driest (1945) during 5 months of the year, January-March and June-July (see graph). From August the accumulated total was larger, but it did turn out to be the 9th driest in Llansadwrn records back to 1929. The driest month was June (30.3 mm) closely followed by March (35.0 mm) while the wettest was February (113.9 mm) followed by November (107.7 mm). Despite being a dry year the number of dry days 114 were only 8 above average but the number of rain days (0.2 mm, or more) 206 was only 1 day below average. Similarly wet days (1.0 mm, or more) 154 were only 4 below average. Falls of 5 mm, or more, were only 58 and 17 below average. This was also reflected in the number of large falls of 25 mm, or more. There were only 2, 26.5 mm on 11 February and 31.6 mm on 28 November, and were 2 below average much less than the 10 seen in 2000. It seems that there was rain little and often but the number of large falls were few and far between.

The annual mean temperature was 9.9C (-0.2) the lowest since 1996 (9.5C). Similarly the mean maximum of 13.0C and the mean minimum of 6.8C were the lowest since 1996. Maximum temperatures, particularly in the summer, were on the cool side with the highest 25.9C on 28 July the lowest since the 25.6 in 1982. Since temperature records began here in 1979 the highest maximum seen in the year ranks the Click for graph daily mean temperature compared with the long-term mean 5th coldest. While the number of days with a maximum of 10C, or more, was 254 (+3) and 15C, or more, 146 (+7) the number of warm days with 20C, or more, was only 27 (-10). The lowest minimum of 5.0C was on 4 March and was the lowest since 1996 (5.2C) but ranks only 9th lowest on record. There were 28 airfrosts (+8 on the 10y 1991-00 average) but -8 on the average on 1981-90: an indication of how warm the last decade has been compared with the previous. It was frost-free from 20 March to 14 December, 270 days. Year 2000 had only 9 airfrosts the lowest, with 1998, on record here. Number of ground frosts were also up at 89 (+21) with the hardest frost of -10.2C on 4 March. A temperature giving good growing conditions for plants is sometimes taken as 5.6C (42F), or more. Maximum air temperatures were above this threshold on 343 days in the year while minimum temperatures were below it on 153 days. The mean was equal or above the threshold on 286 days in the year. In the soil at 50cm and 100cm temperatures were equal to or above the threshold on 310 and 343 days respectively, less than last year (2000). At 30cm the number of days below the threshold was 79 while at 20cm, 10 cm and 5cm the number was 87, 92 and 97 respectively, all greater than last year (2000).

There were 18 days (+5) in the year when sleet or snow was seen to fall. Most (5) occurred in February and December but there were 3 in April. The year with most was 1995 with 35 days and there were none in 1992 (in records back to 1979). Snow was lying on 5 days (+2), 3 were in December. The most number of days with snow lying (10) was in 1985. The number of days with all types of hail was 21 (-5) and in contrast to 2000 that had 45 the largest number on record since 1979. There were 4 days when hail of 5mm diameter, or more, were observed. Thunder was heard on 8 days during the year, about the average, with May being the most thundery month with 3 days.

Sunshine for the year reported at Valley was 1760h some 109% of average. The sunniest month was May with 255h (110%) while the least sunny was November (80%). Distribution through the year, however, was unusual with the main summer months June to September having only average, or below average sunshine, but January to May and December were all well above average.


Complete daily weather diary for 2001.Complete daily weather diary for 2001.
View the complete daily observations for 2001.View the complete daily observations for 2001.



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Monthly data 2001

 Llansadwrn (Anglesey): Monthly weather data for 2001.
(~ Based on the 1991-00 average)

                  Jan    Feb    Mar    Apr    May    Jun    Jul    Aug    Sep    Oct    Nov    Dec     Year

Air temperatures (C)

Mean max          6.9    7.8    9.3   11.0   16.3   17.0   18.9   18.7   16.1   15.8   10.8    7.8     13.0
Mean min          1.4    2.1    2.4    4.4    8.4    9.8   12.0   12.1   10.7   10.7    5.8    2.2      6.8
Mean              4.2    5.0    5.9    7.7   12.4   13.4   15.4   15.4   13.4   13.2    8.3    5.0      9.9
Anomaly~         -1.1   -0.6   -1.3   -1.0   +0.7   -0.2   -0.3   -0.4   -0.4   +2.6   +0.6   -0.5     -0.2
High max         10.6   10.8   14.2   15.3   24.0   25.8   25.9   24.2   22.4   19.3   14.7   12.4     25.9
Date                1     14      6      1     24     26     28      1     28     17      2      8   28 Jul
Low max           4.1    3.0    3.8    7.0   11.6   12.6   14.7   16.2   13.0   12.0    6.0    3.3      3.0
Date               16     28      1     22     15      6     18     14     17     21      8     30   28 Feb
High min          7.3    7.5    7.8    9.4   14.0   15.3   16.9   16.2   15.1   13.4     10    8.1     16.9
Date                2     11      8      2     12     29     29     14     28      2     30      1   29 Jul
Low min          -2.6   -1.6   -5.0    1.0    3.5    3.5    5.9    8.5      8    6.4    1.8   -1.5     -5.0
Date               17      9      4     21      5      8     15  10,28     14     31     26     31    4 Mar
Grass min        -8.3   -6.0  -10.2   -3.0   -0.2    0.9    4.1    5.5    3.0    2.3   -2.6   -6.5    -10.2
Date               16     18      4     21      5      8     15     27     14     28     26     15    4 Mar

Atmospheric moisture means

RH (%)             88     90     87     87     82     80     83     88     88     89     92     85       87
Dew point (C)     1.4    2.3    2.8    5.6    9.6   10.2   12.4   13.1   11.0   10.9    7.0    2.0      7.4

Soil temperatures (C)

5 cm              2.0    3.5    4.7    8.1   13.1   16.0   17.3   16.3   13.7   11.9    8.1    3.6      9.9
10 cm             2.4    3.9    5.0    8.0   12.7   15.0   16.3   16.1   13.8   12.3    8.4    4.3      9.8
20 cm             3.1    4.6    5.6    8.7   13.3   15.2   16.7   16.7   14.6   12.9    9.1    5.3     10.5
30 cm             3.5    5.0    6.0    9.3   13.8   15.7   17.2   17.4   15.3   13.5    9.8    6.0     11.0
50 cm             4.4    5.4    6.2    9.3   13.3   15.3   16.9   17.3   15.6   13.9   10.5    7.1     11.3
100 cm            5.8    6.1    6.6    8.9   12.0   14.1   15.6   16.3   15.3   14.0   11.4    8.5     11.2

Rainfall (mm)

Rain tot         44.0  113.9   35.0  103.8   48.7   30.3   45.9   96.7   98.2   85.7  107.7   56.1      866
Rain % av~         44    129     41    140     74     41     77    130    101     74     83     45       82
Days, dry          12      6     11      4     17     14     12     10      5      8      6      9      114
Days >=0.2         14     20     16     19     12     10     15     20     21     20     21     18      206
Days >=1.0         11     16     12     17      8      6     10     17     11     18     16     12      154
Days >=5.0          2      8      1      9      3      2      3      8      6      6      6      4       58
Max fall         10.4   26.5    5.9   14.4   16.3   14.1   11.2   14.5   19.7   15.6   31.6   12.5     31.6
Date                3     11     31      5     27     14      3     18     30     19     28     25   28 Nov


Piche (mls)      26.0   23.5   35.1   34.0   48.0   49.2   49.6   35.1   34.3   43.9   21.4   30.4    430.5
Lysimeter (mm)   -5.4   -0.3   12.8   24.7   58.9   55.3   53.9   41.7   37.1   11.1   13.0   -5.1    297.7

Weather (days)

Air frost          10      4      6      0      0      0      0      0      0      0      0      8       28
Ground fr          20     17     14     11      1      0      0      0      0      0      4     22       89
Sl/snow             1      5      3      3      0      0      0      0      0      0      1      5       18
Sn lying            0      1      1      0      0      0      0      0      0      0      0      3        5
Thunder             0      0      0      0      3      1      1      1      1      1      0      0        8
Hail <5mm           0      5      2      3      0      0      0      0      0      0      3      4       17
Hail >=5mm          1      0      0      0      0      0      0      0      0      1      1      1        4
Fog at 09h          0      0      1      0      0      0      1      1      0      0      2      0        5
Gales               0      1      1      0      0      0      1      0      1      4      1      1       10

Wind direction at 09h (days)

N                   0      1      2      4      4      4      3      5      7      0      3      3       36
NE                  5      6      4      2      7      5      6      2      5      0      3      4       49
E                   2      1      6      1      4      1      1      1      2      2      0      3       24
SE                  3      0      6      2      1      0      1      1      1      1      0      1       17
S                   3      8      4      7      6      8      4      7      2     12      2      2       65
SW                  3      4      5      5      4      7     11      7      2      9      7      1       65
W                   5      1      2      4      3      3      2      2      4      2      5      5       38
NW                  1      2      0      5      1      1      3      3      6      2      5      4       33
Calm                9      5      2      0      1      1      0      3      1      3      5      8       38

Autographic records of rainfall and frost duration (h)

Rain             43.1   97.4   35.2   88.4   35.7   26.5   43.7   74.9   61.3   70.2   97.7   52.4    726.5
Frost            65.8   24.6   64.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0    0.0   40.9    195.3

Cloud cover at 09 GMT

Mean (%)           58     82     67     83     65     85     77     80     82     70     86     67       75

These pages are designed and written by Donald Perkins © 2001

Page dated 2 Febraury 2001

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