Llansadwrn (Anglesey) Weather:

Note: Values in (.) refer to the 10y 20012010 average; [.] refer to the 30y 19812010 climatological average while {.} refer to the station LTA (longterm average) from 1979. All data are subject to verification and amendment. Javascript must be enabled to see the popup graphics.
The month ended with a mean temperature of 4.3C, (=) highest since 2008, was (1.1) of the decadal and [0.8] of the new 1981  2010 climatological average. Total rainfall was 79.2 mm, highest since 2009, one of the 28 lowest since 1929, was (77%) and [78%] of average. At Valley there were 73.5h of sunshine, sunniest since 2006, rank 11 on the K&Z adjusted Anglesey record since 1930, average (119%) decadal and [127%] 1981  2010. Sunniest 8.1h on 28th; 9 sunless days.
It was the 3rd warmest February since before 1979. The mean temperature 7.0C, highest since 1998, was (+1.7) and [+1.8] of average. Rainfall 96.5 mm, highest since 2004 ranking 23 since 1928, was (119%) and [123%] of average. At Valley sunshine totalled 72.4h (87%) and [91%] of average, highest since 2009 rank 46 since 1930, highest 8.9h on the 28th and here were 7 sunless days.
The driest March since 1993, rank 7 in Llansadwrn since 1928. The 29.4 mm rainfall was (44%) and [35%] of the averages. Since midmonth temperatures pickedup and the mean temperature finished on 7.2C, highest since 2009 rank 15 since 1979, was [(+0.3)] based on both decadal and 1981  2010 averages. A very sunny month at Valley the 168.1h (125%) & 148%] of average, highest since 1955 ranking 4 on the Anglesey record (K&Z adjusted) since 1930. Sunniest day was on the 27th with 10.7h and there were 2 sunless days. In the cloudier Llansadwrn with 5 sunless days mean global solar radiation was 8.18 MJ m^{2}, brightest day was the 26th with 13.41 MJ m^{2}. Brightest hour was from 1200 GMT on the 28th having 648 W m^{2}.
In common with many places it was the warmest April on record. The mean temperature was 11.9C (+2.6) and [+3.0] the highest here since before 1979 when records began. The mean maximum was 15.8C and the mean minimum 7.9C. The highest maximum 24.4C was (+5.4). Rainfall was 45.3 mm highest since 2008, but one of the 28 driest in Llansadwrn since 1928. The mean temperature of the soil at 30 cm depth was 12.1C (+1.8) and [+2.3} of average. At RAF Valley there were 211.1 h of sunshine (125%) & [134%] of average, lowest since 2009 (188h), but ranking 5th sunniest on the Anglesey record since 1930. Sunniest day was on the 28th with 13.6h, there were 5 sunless days. .
Rainfall for the month totalled 79.4 mm (113%) and [128%] of average, largest since 2009 ranking 29 since 1928. In parts of southern Britain spring rainfall totals have been the least for 100years (Met Office). Here spring rainfall was 154.1 mm, largest since 2008 and more than in 2010 (133.9 mm) and considerably more than the 80.2 mm of driest in 1990 ranking 19th since 1928. For the wettest Spring in Llansadwrn look back to 1947 that had 352 mm.
The May mean maximum 15.7C was (+0.2) and (0.2] of average while the highest 20.5C on the 1st was (3.2). The May mean temperature 12.1C (+0.3) and [+0.4] of average was highest since 2008 ranking 9 since 1979. Spring had the highest mean temperature 10.4C on record since 1979. The mean minimum 6.6C equaled 1999, the mean maximum 14.2C ranking 3 equaled 1988 but beaten by 1990 with 14.8C.
It was the dullest May since 2003; sunshine duration at RAF Valley was 175.0h with 2 sunless days (88%) and [90%] of average. Sunniest day was on the 2nd with 13.7h, preceded with 12.1h on the 1st and followed by 13.5h on the 3rd. The 31st with 12.5h was another sunny day.
A very windy month, the mean wind speed at RAF Valley was 18.4 mph (+4.7) and [+5.7], highest since 1986 (20.2 mph), the 7th windiest May in records since 1956.
Temperatures in June were below average, the mean 13.4C was lowest since 1999 ranking 9th since 1979, (1.1) of the decadal and [0.5] of the 30y averages. The lowest minimum 5.0C lowest since 2001 (3.5C) was (1.3) while the soil at 30 cm depth 15.4C was (0.8). The highest maximum here was 25.3C on the 26th, highest since 2009 (26.3C), however, was (+0.5). Llanfairfechan and Hawarden both reported 27.7C, Rhyl 27.0C, Aberporth 25.3C, RAF Mona and Capel Curig 23.4C. Provisionally, the highest in the UK on the day was St James Park with 29.2C. On the 3rd Porthmadog reported 26.1C and 25.4C on the 4th.
Rainfall of 65.5 mm, highest since 2009, was close to the averages (101%) and [97%] bringing rainfall for the first 6months of the year to 395.3 mm ([36%)} below the longtermaverage of 450 mm. The wettest day was on the 12th having 15.6 mm, but the 24th also wet had 15.0 mm. There were 8 (5.0) days with no precipitation and there were 15 (1.2) dry days. Rain days totalled 12 and were (+2.2) and days with 5 mm, or more, were 4 (0.4). Rain and evapotranspiration (66.6 mm by lysimeter) were almost in balance (1.1).
It was a sunny and another windy month at RAF Valley. Sunshine duration was 221.1h, lowest since 2009 but ranking 10 on the Anglesey record (K&Z adjusted values) since 1930, (119) and [129%] of average with the sunniest day on the 3rd with 15.5h and 2 sunless days. The mean wind speed was 13.8 mph, the highest since 1998 (13.2 mph), (+3.3) and [+3.6] of average, ranking 18 in records since 1956.
Rainfall was 67.8 mm, lowest since 2008 ranking 38 since 1928, (79%) of the decadal, but [97%} of 30y average. The wettest day with 17.2 mm was on the 17th that was the first of 3 dull days. No precipitation was recorded on 17 days (+7.4) that were also dry (<0.2 mm) (+3.0). There were 14 (3.0) rain days (>=0.2 mm) and 11(2.3) wet days >=1.0 mm). Despite the lowish rainfall total 7 days had 5 mm,or more (+1.4) suggesting continuation of a trend of "when it rains we get greater falls'. Thunder was heard on the 3rd starting at 2312 GMT with heavier thunder with lightning just before midnight. Further thunder between 0010  0030 GMT with rain falling at up to 113 mm/h during a 20min spell. Rainfall duration was 63.1h recorded autographically and 73 wet hours by the AWS. Rainfall in Llanfairfechan was 76.6 mm with 75 wet hours recorded (wet hours are the number of hours when 0.2 mm, or more, precipitation are logged).
Temperatures were below average. The mean 14.8C (1.0) of the decadal and [0.9] of the 30year average, was lowest since 2007 ranking 9 since before 1979.. The mean maximum was 18.4C (0.9) and [1.1], the highest maximum 24.7C (1.5) was on the 4th. The mean minimum was 11.3C again below the averages (1.1) and [0.7], the lowest minimum 7.7C (0.7) and the lowest grass minimum 4.3C (1.1) were on the 2nd. Mean soil temperature at 30 cm 16.8C and 100 cm 15.5C were (0.7) and (0.5) below average respectively. Potential evapotranspiration measured by lysimeter was 57.9 mm resulting in a potential water balance of 9.9 mm
It was a sunny month at Valley the 233.3 h duration, (146%) and [140%], was highest since 2006 ranking 5th on the Anglesey record since 1930 (K&Z adjusted values). There were 10 days with 10h, or more, the sunniest had 15.5h on the 3rd and there were no sunless days although 2 recorded just 0.1h. In Llansadwrn mean global solar radiation was 16.37 MJ m ^{2}. The brightest day was the 13th with 26.84 MJ m^{2} while the dullest with 3.44 MJ m^{2} was on the 17th. The brightest hour of any day was from 1300 GMT on the 28th receiving 892 W m^{2}.
A cool month the mean temperature of 14.7C [(1.0)] of average, just 0.1C higher than August 2010, it was 9th lowest since before 1979. The mean maximum 17.8C was lowest since 1992. In a warm spell of 3days (2  4th) the highest maximum was 21.6C on the 4th , but was 4th lowest in the station's records. Just 4 days reached 20C, or more, in the month.
The lowest grass minimum 3.8C was 4th lowest since before 1986 when records began.
Rainfall 90.4 mm, highest since 2009, was on the average, ranking 44 lowest since before 1928. The wettest day on the 10th had 37.3 mm (34% of the month's total) was the largest in a day in August at this station since before 1979, just beating the 37.2 mm on August 26th 1992. It was also the wettest any day here since 25th October 2008 that had 52.8 mm. There were 10 dry (<0.2 mm) days (3.5) and 5 days (3.1) with no precipitation. There were 13 wet (1 mm, or more) days (+0.2) and 5 days had 5 mm, or more (0.9). The highest rate of rainfall was 61 mm/h on the 10th; the highest rate in Llanfairfechan was 107 mm/h falling on the 7th during a heavy shower.
It was a dull month with sunshine duration at Valley 138.6h (92%) of the decadal average and just [86%] of the just 86% of average (K&Z adjusted values). The sunniest day with 10.9h was on the 17th while 10.0h was recorded on the 5th. There were 2 sunless days (10 & 11th), and another 5 had <1h the 13th and 29th with just 0.1h each.
SUMMER
Rainfall over the summer months was 223.7 mm (92%) & [99%] of average, lowest since 2006 that had 155.1 mm, and ranks the 37th lowest total in Llansadwrn since 1928 (95% of the LTA).
A cool summer, the mean of 14.3C, (1.0) and [0.8] of average, lowest since 1993, ranked 7 in records since 1979. The mean maximum 17.8C, lowest since 2002, ranked 5 while the mean minimum 10.8C, lowest since 1993, ranked 8.
Large falls of rain spread through the month, high temperatures at the end.
The 152.4 mm of rainfall, largest fall in any month since July 2010 (182.1 mm) and most in September since 2004 (165.8 mm), was (149%) of the decadal and [159%] of the 30year average. It was one of the 16 wettest Septembers in Llansadwrn since 1928. There were 5 large falls of over 10 mm on the 3rd, 5th, 14th, 16th,17th and 25th. The largest fall was on the 25th with 27.8 mm of 5h duration between 1800 and 2300 GMT. Rain was heavy with very some heavy bursts at rates up to 52 mm/h. There was no precipitation on 7 days (2.1) and there were 10 (+0.9) dry days. Rain days totalled 20 (+3.8) and wet days 16 (+4.9). There were 10 (+3.8) that had 5 mm,or more.
The 28th saw the highest temperature of the year 26.4C here, and 26.9C in Llanfairfechan, while 25.1C was recorded on the 29th. These were the highest recorded on these dates, but 28.0C was recorded on 4 September 2005, 26.3C on 5th September 1999 and 26.2C on 21 September 2006. In Llanfairfechan 26.1C was recorded on the 30th. The lowest maximum 13.2C (0.0) was on the 6th. The mean maximum 17.7C was (+0.2) and [+0.4] of average and the mean minimum 11.4C (+0.4) and [+1.1]. The lowest minimum 8.1C (+1.2), 2nd highest on record (9.0C on 7th in 2006) and grass minimum 2.8C (0.3) were both on the 23rd. The mean temperature 14.6C (+0.3) and [+0.7] was highest since 2006 ranking 5 since 1979. The highest minimum 16.8C (+1.9) on the 29th was the highest on record since 1979.
A very windy month at RAF Valley. The mean wind speed 19.2 mph was the highest on record since 1956. The 11th had a mws of 32.4 mph and the 12th 33.4 mph while the 6th had 31.0 mph. The mean maximum gust speed was 36.2 mph with the highest gust 57 mph on the 6th.
Overall a rather dull month. Sunshine duration at RAF Valley was 107.6 h [(84%)] of average least since 2000 ranking 25th lowest on the Anglesey record since 1930 (K&Z adjusted values). Most sunshine was on the 1st with 11.4 h duration while the 28th saw 10.9 h, these were the only 2 days to have 10 h, or more. There were 3 sunless days. In Llansadwrn the mean global solar radiation was 7.97 MJ m ^{2}. The brightest day was on the 1st with 16.48 MJ m ^{2} and the dullest was on the 19th with 3.35 MJ m ^{2}. The brightest hour of any day was from 1100 GMT on the 1st receiving 671 W m^{2}.
Generally dull and damp throughout, briefly cooler in the middle of the month
A very dull month with sunshine lowest since 1968 (graphic left). Sunshine duration at RAF Valley was 60.6h (60%) and [62%] of average based on K&Z adjusted values. Less than in January and February, and lowest of the year so far. The sunniest day was on the 15th having 7.0h and there were 7 sunless days.
Rainfall totaling 112.2 mm was highest since 2008 (the wettest October here on record), (78%) and [87%] of average. There have been 56 Octobers with 100 mm, or more, but October ranked only 38th lowest since 1928. The wettest day was on the 22nd with 17.6 mm. The month managed 4 (4.1) days without any precipitation and there were 8 (3.2)dry days (<0.2 mm). Despite the total being below average the number of rain days (>=0.2 mm) 23 (+3.2) and wet days (>=1.0 mm) 20 (+4.5) were above average making for a rather damp month. Number of days with 5 mm, or more, 9 was also above average (+1.4). There were at times some very heavy bursts of rain. On the 17th in Llansadwrn 103 mm/h while in Llanfairfechan 281 mm/h resulted in instant standing water.
Mean temperatures were well above average. The mean 12.4C, highest since 2006 and ranking 6 since 1979, was (+1.0) based on the decadal and [+1.6] on the 30y averages. The highest mean was 18.9C on the 1st and the lowest 7.4C on the 19th. The mean maximum was 15.0C (+0.6) and [+1.0]. The highest maximum 22.0C (+2.0) was on the first the only day in Llansadwrn >=20C. This brought the number of days >=20C this year to date up to 30, lowest since 2008. Llanfairfechan did rather better with 3days (13 rd) all >20C with the highest 22.0C on the 3rd. The lowest maximum of 10.2C (+0.3) was on the 19th. The mean minimum was 9.8C (+1.4) and [+2.1] , the lowest 3.6C on the 20th was on the average. There were 2 (+0.8) ground frosts, the lowest 0.4C (0.1) was on the 20th.
A sunny and warm and dry beginning. Wet and windy at the end of the month.,
A remarkably warm month the mean temperature 10.3C highest on record at this station (since 1979). Temperature anomalies were (+2.1) and [+2.6] based on the decadal and 30y averages. The graphic (left) shows the differences from the 19792011 mean of 7.7C. The only other November to have a doublefigure mean in over 30years was 1994 with 10.1C, that was the warmest November since records began in Britain in 1659. The mean maximum 13.4C (+2.6) and [+3.0] was also highest on record with the absolute maximum 17.7C (+2.9) on the 3rd running 2nd to the 18.7C of 2003. First indications were that the highest in Britain was 18.1C at Otterbourne, Hampshire, on 13 November. The mean minimum 7.2C (+1.5) and [+2.2] was beaten into 2nd place by 1994 with 7.9C. The highest minimum 13.1C on the 3rd was 2nd highest on record just pipped by 13.5C in 1997. The lowest minimum 2.8C (+2.3), closely following on the 7th, ranked 3rd highest up against 2.9C in 1997 and equal with 1994. First indications were that the lowest was 6.9C at Carleton near Skipton in North Yorkshire on 7 November. There were 3 ground frosts here (3.3) on average with the lowest 1.0C (+2.7) on the 7th following one of the few cloudfree nights of the month when 0.33 mm of dew and frost was recorded. The mean temperature in the soil at 30 cm was 10.1C (+0.8) all daily values were above 5.6C (42F) plant growth benchmark. The highest temperature was 12.0C on the first and lowest 8.6C on the 16th. The mean temperature at 100 cm was 11.6C (+0.5).
It was a sunny month at RAF Valley the 77.9h of sunshine, (134%) and [136%] of average, was most since 2009 and 5th highest on the Anglesey record since 1930 (K&Z adjusted values) despite there being 6 sunless days. The sunniest day was on the 6th having 7.9h, the 15th had 7.5h and another 6 had 5h or more. With the sun much lower in the sky this month the brightest day in Llansadwrn was on the 1st with 9.74 MJ m ^{2} while the dullest was on the 29th with 0.98 MJ m ^{2}. Sunniest in Britain was Kinloss, Morayshire, 101h duration, but Lerwick had only 29h.
It was a relatively dry month the 58.0 mm, just (42%) and [46%] of average, least since 1983 (38.9 mm) and the 10th driest November since 1928. The wettest day was on the 29th with 13.5 mm of rain. 10 days (+5.6) had no precipitation while 14 (+6.3) were dry with <0.2 mm. There were 16 (6.3) rain days and only 8 (10.4) wet days. There were just 4 days (5.0) that had 5 mm, or more. Wettest in Britain (first indications) was Inveruglas, Dunbartonshire, with a total of 402 mm in the month while the driest was Bridlington, East Riding of Yorkshire, with only 11 mm.
There was a potential water balance of 46.5 mm. The total January to November was 876.1 mm below the longterm average 966.8 mm . The stylized graphic on the left shows the dynamics of rainfall, evaporation and water balance at the end of the month. Soil moisture reached a low point of 31% dry mass at the beginning of May (well above the permanent wilting percentage that is 15% in the local soil), but the above average rainfall went towards restoring the balance and soil moisture . Potential evapotranspiration (PE) was highest in June and reduced the balance again despite average rainfall. The relatively dry November saw a reducing the water balance, but as PE is much lower at this time of year soil moisture (62% dry mass on the 18th) had been slowly increasing. While most of northern and western Britain have an excess of moisture there has been a lack of rainfall in the southern of Britain there have been concerns that if winter rains are not forthcoming then soil moisture and ground water supplies could remain low into the summer.
There was no ice precipitation in the month, the first time this has occurred since 1994. There are only 6 Novembers with zero records of ice precipitation since 1979. In recent years there has been a trend of increasing days with ice precipitation, last November 2010 had 14 days, the highest number since 1979.
AUTUMN
Autumn mean temperature was 12.4C (+1.1) & [+1.6] , highest since 2006 (12.6C) and 2nd highest in records here since 1979. The mean maximum 15.4C (+1.2) & [+1.5] also highest since 2006 (15.8C) again 2nd highest in the station's records. The mean minimum 9.5C, however, was highest overall (+1.1) & [+1.8].
Autumn rainfall was 322.6 mm, (84%) & [92%] of average, ranked 36th lowest in records since 1928. It was highest since 2009, but fell far short of the record autumn rainfall of 612.1 mm in 2000.
Colder, wetter and windier in the first half of the month.
It was the least sunny December on Anglesey since 1931 with a few hours more than the lowest duration 14.4h in Holyhead (K&Z adjusted values, the CampbellStokes recording was 15.5h . Sunshine duration recorded at RAF Valley was 21.3 h (40%) & [45%] of average. The sunniest day was on the 28th with 3.2h and there were 13 sunless days.
A mild month generally, the mean temperature 6.0C (+0.7) & [+0.6] was equal lowest since 2007 ranking 23 since 1979. The highest mean was 10.7C on the 26th, the only one to be in double figures, while the lowest was 2.2C on the 16th. The mean maximum was 8.3C (+0.6) & [+0.5] the highest was 11.5C on the 26th (0.3), one of 10 to reach double figures. The maximum temperature reached 13.9C at Gorwel Heights in Llanfairfechan on the 25th, 13.5C on the 31st and 13.3C on the 22nd during Föhnevents. The lowest maximum was 5.0C, this (+2.4), on the 5th and 16th. The lowest minimum was 0.7C (+1.9) on the 16th and with the 17th the only days having airfrost. The highest minimum was 9.8C (+0.9) on the 26th. There were 16 days with ground frost (0.7), the lowest recorded was 4.2C (+3.0) on the 16th. There were 17 days with ice precipitation, the highest on record beating the previous highest 14 in November 2010, mostly snow pellets and small ice pellets. Snowflakes fell along with snow pellets on the 9th and 10th, but there was no lying snow.
Precipitation totalled 146.4 mm (129%) & [121%] highest since 2006 and ranking 23 in records since 1928. The month joined 57 other Decembers in having over 100 mm of precipitation. The wettest day was on the 12th with 17.0 mm, the 2nd and 9th each had 14.2 mm while the 22nd had 11.5 mm. There was just 1 day (6.8), the 13th, with no precipitation recorded and there were only 2 dry days (10.3), the 21st having a trace. Rain days were 29 (+10.3) and wet days 24 (+9.5). There were 12 days (+4.1) that had 5 mm, or more. Soil moisture levels increased and by the 14th pools of water were seen on surrounding fields and were near saturation at the weather station by the 23rd.
A very windy month, the mean wind speed at Valley was 19.4 kt (22.4 mph), the highest recorded since 1968 (22.7 mph) and 3rd highest on record since 1956, 25.5 mph in 1974. Gales were reported on the 1, 8, 12, 13 & 14th. The windiest day was on the 13th with a mws of 37 mph. Gusts of 65 mph were recorded at Valley on the 1st and at Gorwel Heights in Llanfairfechan on the 12th. A gust of 48 mph was recorded in Llansadwrn on the 8th.


I am grateful to Geraint Roberts, at the Met Office RAF Valley, for providing the observations at Valley; and thanks also to deputy observers Fran and Evan Hennessey for making careful observations through the year.
These pages are designed and written by Donald Perkins © 2011 Page first dated 12 June 2011 http://www.llansadwrnwx.co.uk 