January 2010Cold, dry and mostly sunnyCold beginning and end with frequent ice precipitation. Dry and sunny in the middle of the month, wettest at the end The first 15 days had a mean temperature of 1.2C well below the average of the past decade (4.5) and 30y 19712000 [3.7] monthly averages. The 10 air frosts were (+7.0) and 15 ground frosts (+2.4). Days with sleet/ snow were 10 (+8.3) and snow lying 9 (+9.0). Precipitation was 18.0 mm (16%) and [18%] of the monthly average. The monthly mean maximum of 5.2C, was lowest since before 1980, (2.9) and [2.2] of average. The mean minimum was 0.7C, equal lowest since 1997 ranking 4, (2.5) and [1.7]. The mean was 3.0C, lowest since 1985 ranking 3, (2.7) and [1.9] . Total precipitation was 52.6C, lowest since 2001 rank 13 since before 1928, (52%) and [60%]. Most 12.4 mm was on the 28th. There were 5 days (2.5) with no precipitation and 10 (1.3) dry days (dry days are those having <0.2 mm). Rain days (those with 0.2 mm, or more were 21 (+1.3) while wet days (those with 1.0 mm, or more) were 15 (0.0). Days with 5 mm, or more were 4 (3.2). Air frosts were 13 (+9.0), lowest was 4.2C on the 4th with a duration of 119.0h. Ground frosts were 23 (+10.4) with the lowest 8.4C (2.6) on the 8th. Snow, or sleet, fell on 14 (+12.3) days and there were 10 days with snow lying at 09 GMT deepest was 3.0 cm on the 7th. Sunshine duration at RAF Valley was 67.4h (111%) and [123%], highest since 2006 and 15th highest on the Anglesey record since before 1930. Sunniest 6.6h on 8th, there were 6 sunless days.
February 2010Temperatures and rainfall below averageMixed weather throughout The mean temperature of 3.5C (2.2) and [1.8] of average was lowest since 1991 ranking 4 since before 1979. The mean maximum 6.5C [(2.0)] was lowest since 1996; the highest 12.8C (1.8) was on the 24th, one of only 2 days to reach double figures. The lowest maximum 3.8C (0.2) was on the 19th. The mean minimum 0.4C (2.4) and [1.7] was lowest since 1996; the lowest minimum was 2.2C (0.7) on the 19th. There were 11 days with air frost (+6.9) having a duration of 74.3h. The were 10 days with sleet or snow, equal highest 1996 ranking 2 since before 1979, and 3 days with snow lying at 09 GMT, most since 2006. Another dry month with precipitation totalled 46.2 mm, largest since 2008 but ranking 23 lowest since before 1928, (51%) and [62%] of average. There were 4 (2.5) days with no precipitation and 16 counted as dry days (<0.2 mm falling). Rain days (>= 0.2 mm) were 12 (5.6) and wet days (> 1.0 mm) 10 (2.8). There were 3 days that had 5 mm, or more, the largest was just 8.4 mm on the 14th. It was the sunniest February since 2008, one of the 17 sunniest on the Anglesey record, with sunshine duration at Valley 92.1h (111%) and [122%]. Sunniest day was on the 17th with 8.9h, there were 3 sunless days. March 2010Temperatures a little below average, near average rainfall and quite sunnyA very dry beginning, wet middle and end The first 15 days were remarkably dry with just 0.2 mm measured rainfall. The mean temperature 4.6C was well below normal (2.4) and [2.1] of average and there was ground frost every night. Sunny with 109 h reported at Valley already (83%) and [103%] of the average for March . A wetter second half of the month brought precipitation up to 84.5 mm, highest since 2008 ranking 27 since 1928, (133%) and [100%] of the averages. There were 17 (+2.7) dry days, 11 (+1.7) of which had no precipitation at all. There were 14 (2.7) rain days and 11 (1.0) wet days while 5 (+1.1) reached 5 mm, or more. The wettest day was on the 30th with 21.3 mm falling. The mean temperature 6.4C, lowest since 2006, ranked 11 since before 1979, was (0.7) and [0.4] of the averages. The mean maximum reached double figures with 10.1C (0.3) and [0.1], the highest 15.1C (1.4) on the 25th. The mean minimum was 2.6C (0.7) and [0.4] with the lowest 2.5C (0.5) on the 7th and 8th. There were 8 days with air frosts having a duration of 61.7h. Ground frosts were 18 (+6.0), there lowest recorded was 7.0C on the 8th. Not much in the way of ice precipitation, just 1 day (1.8) the 31st with snow, and 2 days (3.4) with hail. The 147.0 h sunshine duration at Valley was sunniest since 2007, rank 10 on the Anglesey record since before 1930, and (112%) and [139%] of average. Sunniest day was on the 7th with 10.8h; there were 4 sunless days. April 2010A dry and sunny month with temperatures above the 30year averageA cold and wet beginning then turning sunny,warmer and very dry with a drought between 7  23rdThe first 15 days had rainfall of 18.4 mm (25%) and [32%] of the month's average and by the end of the month had risen to just 20.8 mm, lowest since 1984, (28%) and [36%] of average ranking 7 since 1928. The 17 days between 7  23rd had no measurable rain and qualified, under former terminology, as an absolute drought. The wettest day on the 4th had 11.1 mm, and the only one to have more than 5 mm (4.4). Wet days were 3 (9.9) and rain days 8 (8.4). Dry days (<0.2 mm) were 22 (+8.4) and those with no precipitation 17 (+7.2). Evaporation rates were 58.3 mm by Piche evaporimeter and 49.8 mm PE measured by lysimeter. The potential water balance was 29.0 mm. On the 27th soil moisture measured under grass had fallen to 43% dry mass from over 61% at the beginning of the month.The mean temperature 8.2C was below and both the decadal (0.9) and 30y [0.4] averages. By the end of the month the mean temperature was 9.1C (0.1) and [+0.5], lowest since 2006. The mean maximum was 13.4C [(+0.6)] of average, the highest maximum was 18.8C (0.0) on the 24th and the lowest 9.5C (+2.0) on the 2nd. The mean minimum was 9.1C below the decadal average (0.7) but above the 30y average [+0.4]. The lowest minimum was 0.4C (0.3) on the 1st, so no air frosts, but there were 10 (+3.7) ground frosts with the lowest temperature on the grass 4.2C on the 22nd, unusually quite a spread in the dates of these minima. The mean soil temperature at 30 cm deep was 9.9C (0.3) It was the sunniest April since 2007, the 222.9 h duration recorded at Valley was the second highest on the Anglesey record since 1930, (137%) and [142%] of average. The sunniest day on the 16th had 12.8h, there were no sunless days.May 2010Exceptionally sunny, rather dry, but mean temperatures below averageDry and cool at the beginning, highest temperatures after midmonth with most rainfall at the end.An exceptionally sunny month at Valley the 271.9 h sunshine duration {(140%)} of both Kipp & Zonen adjusted averages. Despite 2 sunless days it was the sunniest May on the Anglesey record since 1930, beating the previously sunniest 1977 that had 257.7h (K &Z adjusted value). The sunniest day was on the 23rd with 14.7h. May is second only to April being the driest month of the year, and rainfall this month was true to form with 28.6 mm (39%) of the decadal and [50%] of the 30year average, lowest since 1998 (25.3 mm) ranking 8 since 1928 in Llansadwrn. The wettest day was the 31st having 7.5 mm, but only because of the statistical curiosity in that a days rainfall is totalled between the hours of 09  09 GMT. The 31st rain fell after midnight on the 1st June! The 28th had 6.9 mm. Days with no precipitation titled 18 (+6.5) while dry days with <0.2 mm were 20 (+5.4). Rain days were 11 (5.4) and wet days were 7 (5.7). Just 2 days had >5 mm (2.6). Evaporation totals were moderately high with the Piche evaporimeter recording 61.9 (ml) mm and the lysimeter a PE value of 73.5 mm. Potential water balance (PWB) was 44.9 mm. The potential water deficit (PWD) was 52.6 mm. Soil moisture sampled under grass fell from 37.5% dry mass (DM) on the 4th to 24.2% DM on the 28th. The permanent wilting percentage for the local soil is 15.2%. On the 23rd leaves on some tall mature sycamores were wilting during the afternoon. There were 4 warm days (>20C) between 20  23rd, the highest was 24.8C (+1.1) on the 23rd. In a rather cool month temperatures on these days failed to bring the mean temperature 10.8C up to the averages so finished (1.1) and [0.7]. The highest mean was 19.9C on the 23rd while the lowest was 7.2C on the 9th. The mean maximum 14.9C was (0.7) and [1.1], the highest 24.8C on the 23rd the lowest 10.2C (0.4) on the 11th. The mean minimum was 6.7C (1.5) and [0.3], the lowest 2.5C (1.1) was on the 12th that also recorded the lowest grass minimum temperature of 0.5C (0.8). There were 3 days of ground frost (+2.3), but no air frosts. The mean soil temperature at 30 cm deep was 13.2C (0.4). There was no thunder, but there were 2 days (+0.5) with small hail (snow pellets) and 2 days (+2.0) on which sleet fell (2nd and 11th). June 2010Sunny, warm and mostly dryWet days beginning and end, otherwise warm and sunnyApart from 2 wet days June was very dry. On the 7th there was 14.3 mm and on the 28th 26.1 mm fell in a thunder storm, these accounting for 92% of the 47.7 mm total rainfall, lowest since 2006, for the month (75%) and [72%] of average. The were 23 (+7.6) dry days and 7( (7.6) rain days. There were just 2 days over 5 mm (2.5). The 14days from the 14th to 27th had no measurable rain, missing out on the 15days required for a drought as in April. Rainfall for the first 6 months of the year was 286.4 mm the least in Llansadwrn since 1929 (283.7 mm). Potential evaporation measured by the Piche evaporimeter was 63.2 mm and by lysimeter 77.1 mm. The potential water balance was 29.4 mm. Soil moisture on the 17 June was 26% dry mass. It was the sunniest June at Valley since 1975. The 251.7 h duration, (142%) and [149%] of average, was the 3rd highest on the Anglesey record since before 1930 using Kipp & Zonen adjusted values. The sunniest day was on the 15th with 15.3 h. There were 14 days with sunshine of 10h, or more. There was 1 sunless day at Valley on the 6th. Temperatures were above the averages. The mean maximum was 19.0C (+1.1) and [+1.3]. The highest maximum was 24.5C (0.8) on the 26th and the lowest 13.9C (+0.7) on the 1st. The mean minimum was 11.0C (+0.3) and [+1.5]. The highest was 14.6C (0.6) on the 27th and the lowest 7.2 (+0.9) on the 20th. The 20th also had the lowest grass minimum temperature of 3.8C (+0.4). Thunder was heard on the 13th when heavy rain and ice pellets fell in Llanfairfechan. On the 29th there was heavy thunder and lightning on a cold front that passed over just after midnight. Disruptions to power supplies were experienced in a large part of SE Anglesey, including Beaumaris. Heaviest rain fell in nearby Red Wharf Bay and Pentraeth. July 2010The wettest July on record in Llansadwrn, dull with mean temperature close to averageSome rain throughout the month, no falls very large. Sunniest at the beginning, maximum temperatures below averageIt was the wettest July on record since 1928 in Llansadwrn continuing a run of wet Julys since 2006 ending the period of mostly drier than average (77 mm) since 1975. The 182.1 mm (243%) and [287%] exceeded the previous largest total of 171.2 mm recorded in 1938 by over 10 mm. There were no exceptional falls, 20.2 mm was the largest on the 19th. There were 11 falls of 5 mm, or more (+5.9) and 19 (+6.5) wet days and 25 (+9.1) wet days. There were just 3 (7.7) with no precipitation and 6 (9.1) dry days. Potential water balance determined (by lysimeter) was 136.7 mm and soil moisture that began the month with 28% dry mass as a result rose to 43% dry mass by the 25th. Potential evapotranspiration was 45.4 mm.
It was a cloudy and rather dull month with 121.4 h of sunshine recorded at RAF Valley, (73%) and [72%] of the Kipp & Zonen adjusted averages. It was the 9th dullest July on the Anglesey record since 1930. The sunniest day was on the 3rd with 12.2 h and there were 6 sunless days with another 3 having <1.0 h. The mean temperature was 15.7C, lowest since 2007 close to the averages (0.1) and [+0.1] so middle of the road. This hid the differences between maximum and minimum values. The mean maximum 18.7C lowest since 2007, and ranking 11th, was (0.6) and [0.8] with the highest 22.1C on the 26th a large (4.1) below average. The mean minimum was 12.7C highest since 2006, and ranking 6th, was (+0.4) and [+0.1]. The lowest minimum 10.0C on the 17th was (+1.8). The lowest grass minimum on the 5th was 6.2C (+0.9). There were 3 days with gales with 2 spanning overnight on the 15/16th causing widespread damage to ash trees on Anglesey and moored boats in the Menai Strait, and around western coast of Gwynedd and Anglesey. Thunder and lightning occurred on the 14th and 22nd. August 2010Only half the average rainfall, temperatures well down and sunny at timesRainfall of 51.3 mm was lowest since 2003 ranking the 14th driest August in Llansadwrn since 1928. Just (51%) of the decadal and [64%] of the 30y averages there were 9 (+1.2) days without precipitation and 14 (+0.8) dry days (<0.2 mm). The wettest day was on the 19th with 12.8 mm. Rain days were 17 (0.8) and wet days 10 (3.3). There were 2 (4.6) with 5 mm, or more. Potential evaporation measured by Piche was 41.5 mm while the lysimeter recorded 37.0 mm. The potential water balance was 14.3 mm and soil moisture under grass averaged 47.1% dry mass varying little through the month. Temperatures were all below average with the mean air temperature 14.6C (1.1) and [0.7] lowest since 1993 ranking 8th since 1979. Warm days were few and far between with 5 days reaching 20C, or more. The mean maximum 17.9C was (1.2) and [1.4] with the highest 21.0C on the 22nd (3.9) of the average. The lowest maximum was 14.7C on the 30th this (0.4) of average. The mean minimum was 11.4C (1.0) and [0.0} with the lowest 7.2C on the 31st. The lowest grass minimum also on the 31st was 2.8C (2.7). Sunshine at RAF Valley was 175.0h duration, (115%) and [107%] of the Kipp & Zonen adjusted averages. Highest since 2005 and ranking 20th on the Anglesey record since 1930.. The sunniest day was on the 15th with 12.4h and there were another 4 days having 10h, or more. There was 1 sunless day. It was windy at times with gales on the 28 and 29th and strong to galeforce winds on the 22nd and 26th. Thunder was heard on the 27th and Ice pellets fell on the 30th. September 2010Rather wet, but temperatures above the 30y average and sunshine close to normalSome dry days spaces through the month, very wet in the middle and warmest at the beginning Rainfall of 123.3 mm, most since 2004, was (119%) and [134%] of the averages and ranked the 25th wettest September since before 1928. The wettest day was on the 18th having 33.0 mm spread over 20.5 h duration. The 26th was wet too with another 13.5 mm, the 2day event clocking up 46.5 mm that was 57% of the month's total. There were, however, 8 days (1.1) without precipitation and 13 dry days (+3.9), those are days with <0.2 mm recorded. Rain days were 17 (+0.6) and wet days 12 (+0.4). There were 8 days (+1.4) that had 5 mm, or more. The mean temperature 14.2C was highest since 2006 ranking 10th highest since 1979 equal to the decadal average but [+0.8] based on the 30y average. The mean maximum was 17.3C (0.1), but [+0.3) based on the 19712000 climatological average. The highest maximum 22.1C (1.1) was on the 3rd one of a spell of 4 days at the beginning of the month with a maximum >=20C. Another 2 days 8th and 9th with maximums of 21.8C and 20.4C respectively making a total of 6 days exceeding 19.9C. The lowest maximum was 11.7C (1.7) on the 24th. The mean minimum 11.0C was equal to the decadal average, but [+1.3] on the 30y average, the lowest 5.8C on the 26th was (1.1). There was no ground frost with the lowest temperature seen on the grass 2.9C (0.2) on the 27th. At RAF Valley it was sunniest since 2006 with 130.3 h of sunshine [(103%)] of average (K&Z adjusted). The sunniest day was on the 3rd with 12.4h while there were 3 sunless days recorded. October 2010Sunny and fairly dry with near average temperaturesRain was scattered through the month, driest warm and sunny during the second week.Sunshine recorded at RAF Valley was 131.8h (136%) and [139%] of average, the most since 1965 and ranking 2nd on the Anglesey record since 1930 using K&Z adjusted values. The sunniest day was on the 11th with 10.4h and along with the 12th having 10.0h were the only 2 days reaching double figures. There were 4 sunless days and another 4 had <1 h. For October here it was a fairly dry month with 87.7 mm, lowest since 2007, just (56%) of the decadal average, but [78%] of the 19712000 average. Driest since 2007 the month ranked 23rd in records since 1928. The wettest day was on the 5th with 16.5 mm, this following on from the 13.5 mm on the 2nd. There was a drier spell up to the 22nd when 13.6 mm fell. A 4th day to have >10 mm was the 30th with 10.2 mm and the 26th had 5.1 mm. There were 10 days (+2.8) without any precipitation and 12 dry days (+1.8). rain days were 19 (1.8) and wet days 14 (2.4). There were 5 days (3.7) with 5 mm, or more. The mean temperature was 10.9C,lowest since 2008, was down on the decadal average (0.4), but up on the 30y average [+0.4]. The mean maximum was 13.8C (0.6) and equal to the 19712000 average. The highest maximum 22.8C was on the 8th and was (+3.1) of average, but the only day to reach 20C, or more, as the previous day reached 19.9C. The lowest maximum 8.9C (1.1) of average, on the 20th, was 1 of only 3 sub10C days in the month. The mean minimum was 8.0C (0.3) and [+0.7]. The highest minimum was on the 9th with 13.4C (+1.0) while the lowest 1.7C (2.0) was on the 25th. The lowest grass minimum 2.4C (2.3), the first ground frost of the season, was on the 21st and was lowest in October since 2008 when 4 ground frost were recorded. There was another ground frost 1.5C on the 25th. November 2010Sunny with below average rainfall, but with some of the lowest temperature since 1993Wet at the beginning turning cold by the middle with frequent snow pellets and snow by the end Sunshine duration at Valley was 84.5h (161%), the highest on the Anglesey record in November since 1930 (K&Z adjusted data). The sunniest day was on the 20th having 7.3h and there were 4 sunless days. Rainfall, 108.9 mm and duration 81.5h, was lowest since 2008 ranking 35 since 1928, was (72%) and [87%] of the average. Largest was 20.2 mm on the 7th, but the 2nd had 16.2 mm. There were 3 days with no precipitation (1.1) and 7 days (0.2) dry days Rain days titled 23 (+0.2) while there were 18 (1.2) wet days. There were 7 days (3.1) with 5 mm, or more. The mean temperature 6.3C was (2.0)and [0.9] of average. Highest 9.8C ranked 8 since 1979, but the lowest minimum 4.1C was lowest here in November on record. Air frosts were on 4 days (+3.7) having 47.4h duration, and there were 11 (+4.4) ground frosts. The lowest minimum on the grass on the 29th 8.4C (5.2) was the lowest record here in November since before 1985. There were 14 days on which small hail was recorded, snow pellets and, or ice pellets. Snow grains were observed on the 21st. Thunder was heard on the 15th.
December 2010Record low temperatures and a foot of snowA remarkably cold and snowy month Several records over 32years were broken this month including number of days with sleet, or snow, and number of days with lying snow that were the most at this station in any month since I began observations in Llansadwrn. The month ended with a mean temperature of 1.8C, lowest in December since before 1979, (3.9) and [3.7] of average. The lowest mean was 5.1C on the 20th and there were a record 4 icedays on the 17th, and 19th  21st, when the temperature failed to rise above zero in the 24h period. The 18th was a near miss when the temperature rose to 1.0C around noon. The mean maximum 4.3C, also lowest recorded, was (3.8) and [3.6] of average. The highest maximum 9.8C (2.4) occurred after the cold spell on the 29th and 30th. The lowest maximum 1.2C (4.0) was on the 20th and was lowest since 12 January 1987 (2.3). The mean minimum 0.7C, equal lowest with 1981 ranking 2, was (4.0) and [3.8] of average. The lowest minimum 9.0C (6.8) on the 20th was lowest on record beating the 8.0C recorded on 12/ 13 February 1985. There were 20 air frosts, equaling 1981 (rank 2), with 256.4 h of frost. There were 23 ground frosts the most since before records began in 1985. Precipitation, mostly snow and snow pellets, titled 69.8 mm (57%) and [61%], was lowest since 2001, ranking 13 in Llansadwrn records since 1929. Largest were 15.9 mm and 14.6 mm, both water equivalent of snow, on the 16th and 21st. Snow lying averaged 26.5 cm on the 22nd, the deepest level snow measured 32 cm, just over a foot of snow! Days with sleet or snow falling 14 (+11.1) and lying snow 14 (+13.1) were most in any month; and days with hail (mostly snow pellets) 13 (+6.4) were second only to November this year. Annual 2010Temperature and rainfall below average, sunniest year on record at Valley
> Monthly data 2010
AcknowledgementsI am grateful to Fran and Evan Hennessey for making observations at the weather station in my absence; and, Geraint Roberts, at the Met Office RAF Valley, for supplying observations at Valley.
