Alternating spells of colder and warmer weather Rainfall of 48.0 mm (42%) & [47%] of averages, was least since 1997, ranking 11th in records back to 1928. The wettest day in terms of volume was on the 8th with just 9.2 mm. This fell over 5 hours duration, but on the 6th there were 14 h when it rained and only 7.2 mm was collected. Another damp day was on the 14th when 6.2 mm fell over 10 h duration. Four days had no precipitation what so ever. (-0.8) of average. Dry days that allow for <0.2 mm of rain, and may include other precipitation including dew, were 12 (+3.3) of average. Rain days(>=0.2 mm) numbered 19 (-3.3); wet days (>=1.0 mm) were 12 (-6.1); and days having 5 mm, or more, were 4 (-4.4). All categories were below average except dry days. At Gorwel Heights it was a little drier with 38.6 mm falling [34%] of average. Dry days were 10; rain days 21; wet days 10; and only 2 had 5 mm, or more. Temperatures were above average for most of the month. The mean 5.7C was lowest since 2015, but was (+0.4) & [+0.6] of averages and ranked 13th warmest of the last 38-years. The highest maximum on the 30th was 12.7C (+0.2) & [+0.5] and the lowest 3.7C on the 12th was (+0.7). The lowest minima were in air 3.3C (+0.5) & [+0.7] on the 12th and on the grass -6.5C (-0.2) was recorded on the 5th and 26th. Earth temperatures were at 30 cm 6.1C (+0.7) and 100 cm 7.7C (+0.5). At Gorwel Heights the mean temperature was 6.8C [+0.5]; the highest maximum 15.1C on the 31st and lowest minimum 0.6C on the 22nd.
Alternating spells of colder and warmer weather
Rainfall of 48.0 mm (42%) & [47%] of averages, was least since 1997, ranking 11th in records back to 1928. The wettest day in terms of volume was on the 8th with just 9.2 mm. This fell over 5 hours duration, but on the 6th there were 14 h when it rained and only 7.2 mm was collected. Another damp day was on the 14th when 6.2 mm fell over 10 h duration. Four days had no precipitation what so ever. (-0.8) of average. Dry days that allow for <0.2 mm of rain, and may include other precipitation including dew, were 12 (+3.3) of average. Rain days(>=0.2 mm) numbered 19 (-3.3); wet days (>=1.0 mm) were 12 (-6.1); and days having 5 mm, or more, were 4 (-4.4). All categories were below average except dry days. At Gorwel Heights it was a little drier with 38.6 mm falling [34%] of average. Dry days were 10; rain days 21; wet days 10; and only 2 had 5 mm, or more.
Temperatures were above average for most of the month. The mean 5.7C was lowest since 2015, but was (+0.4) & [+0.6] of averages and ranked 13th warmest of the last 38-years. The highest maximum on the 30th was 12.7C (+0.2) & [+0.5] and the lowest 3.7C on the 12th was (+0.7). The lowest minima were in air 3.3C (+0.5) & [+0.7] on the 12th and on the grass -6.5C (-0.2) was recorded on the 5th and 26th. Earth temperatures were at 30 cm 6.1C (+0.7) and 100 cm 7.7C (+0.5). At Gorwel Heights the mean temperature was 6.8C [+0.5]; the highest maximum 15.1C on the 31st and lowest minimum 0.6C on the 22nd.
Fairly mild, windy and dull - temperatures and rainfall above averages
Wettest at the end of the month
A mild month generally with the mean temperature 6.5C (+0.9) & [+1.2] of averages, highest since 2011, ranking 7th highest in station records. The mean minimum showing the greatest anomalies was 4.1C (+1.5) & [+1.9] of averages, again highest since 2011 and ranking 4th. The highest minimum was 8.3C on the 18th while the lowest -0.3C and the only air frost was for only 2 hours duration. The mean maximum showing the smallest anomaly was 8.9C (+0.4) & [+0.6] of averages with the highest 14.3C on the 2nd and lowest 4.2C on the 10th. There were 12 ground frosts (-3.7) the lowest recorded was -5.6C on the 9th. At Gorwel Heights the mean temperature was 7.3C [+1.4]. The highest maximum was 14.7C on the 18th; the lowest 3.8C on the 10th. The mean minimum was 4.8C with the highest 9.1C on the 21st and lowest 0.7C on the 10th with no air frosts recorded.
Although rainfall was above average the total was modest for February totalling just under the 100 mm mark with 97.8 mm. This was (138%) & [124%] of averages and was lowest since 2015 and ranked 26th largest since 1928. The wettest day was on the 22nd with 19 wet hours and 18.0 mm rainfall. Another 17.0 mm fell on the 25th this having 15 wet hours. There were 3 (-2.6) days with no precipitation and 8 (-2.7) days were recorded as dry. Rain days were 20 and these were (+2.4) of average and wet days 14 (+2.2). Days with 5 mm, or more totalled 8 and were (=3.5) of average. Wet hours totalled 142 and the average rainfall per wet hour was 0.7 mm. At Gorwel Heights rainfall was 84.0 mm [108%] of average. The wettest day was on the 3rd with 14.2 mm and wet hours were 125 with an average fall of 0.7 mm per wet hour.
It was a dull month with only 49.2 h of sunshine recorded at RAF Valley, dullest since 2012 and ranked the 7th lowest on the Anglesey record since 1931.
Last winter was the warmest and wettest on record in Llansadwrn. No records broken this winter, but it was the 3rd warmest on record the mean 6.7C (+1.1) & [+1.4] of averages while rainfall of 234.6 mm, lowest since 2010, ranked 19th lowest since 1928
There were 9 air frosts, lowest since 2013/14, ranking 10th in records since 1979/80.
There were 39 ground frosts, lowest since 2007, ranking 11th in records since 1985/86
Sunshine recorded at RAF Valley was 139.3 hours lowest since 2012, 8th lowest since 1931.
Wet and warm, but rather dull
Wettest since 2006; warmest since 2012; sunshine lowest since 2006. Brief cool spell 21 - 22nd.
With predominately 19 days with S-SW'ly winds rainfall totalled 135.6 mm and this was the largest in March since 2006 ranking 8th in Llansadwrn since 1928: 213% above the decadal average and 159 % above the 3-y average. The number of Marches with more that 100 mm is now 16, the second driest month of the year second only to April with 8 years. The wettest day was on the 30th with 19.2 mm, but the first had 17.2 mm and the 5th 13.6 mm. There were 13 days that had 5 mm or more 8.9d above average. Wet days were 9.0d above average with 20 days. There were, however, 5 days (- 4.2) with no precipitation ; 8 dry days (-7.8); 23 rain days (+7.8); and 20 wet days (+9.0). On four morning there was standing water other wise the soil was moist every day. At Gorwel Heights rainfall was 114.4 mm [132%] of average and the wettest day here was 15.4 mm on the 6th. Dry days were 10; raindays 21; wet days 18; and days with 5 mm, or more, were 10. Wet hour duration was 143 with an average of 0.8 mm per hour. In Llansadwrn wet hours were 165 with an average of 0.8 mm per hour.
A generally warm month with highest than average temperatures. The mean in Llansadwrn was 8.3C (+1.6) & [+1.3] of averages, highest since 2012 ranking 3rd since 1979. The mean maximum was 11.4C with the highest 17.4C (+1.4) on the 27th and the lowest 5.2C (-0.1) on the 5th. The mean minimum was 5.2C (+1.8) & [+1.6] again ranking 3rd. There was no air frost and there were 8 (-6.0) days with ground frost the lowest -3.8C on the 1st of the month. The mean temperature at Gorwel Heights was 9.1C [+1.7] with the highest maximum 16.5C on the 30th and the lowest 6.4C on the 5th. The mean minimum was 6.2C with the highest minimum 12.4C on the 30th and the lowest 1.6C on the 1st.
There were some very dull days with 8 of them sunless. The lowest solar radiation recorded was 1.64 MJ m -2 on the 11th while the highest was 14.97 MJ m -2 on the 25th. Sunshine at RAF Valley was 109.6h, lowest since 2006 ranking 32 on the Anglesey record since 1931. The sunniest days were on the 24th with 11.1h and the 25th 11.0h
A dry, but dull month with near average temperaturesGenerally light winds from the S-W, cooler and brighter later in the month
A generally dull month with sunshine at RAF Valley 117.9h lowest since 2005 and 10th lowest on the Anglesey record since 1931. The sunniest day was on the 8th with 12.5h recorded. The highest solar radiation recorded in Llansadwrn was 23.66 MJ m -2. on the 26th and the brightest hour from 12-13 GMT was 834 W m -2 on the same day. The dullest day was on the 14th having 4.38 MJ m -2 and there were 4 sunless days.
It was a dry month with only 22.0 mm (41%) & [35%] of averages, lowest since 2010 and ranking 6th lowest in Llansadwrn since 1928. The wettest day only had 6.6 mm, the only day, that was on the 14th. Days with no precipitation were 14 (+2.4) and there were 16 dry days (0.0). Rain days were 14 (0.0) and wet days 9 (-0.5). Gorwel Heights had 26.0 mm [41%], the most in a day was 5.2 mm on the 28th.
Mean temperatures were close to the averages: in Llansadwrn 9.0C (-0.3) and [+0.1], highest since 2014, and at Gorwel Heights 9.5C [+0.6]. The highest maxima were 18.8C (+0.1) in Llansadwrn on the 8th and 16.9C at Gorwel Heights on the 9th.
Warm, dry and sunnyA spell of very warm sunny weather in the second half of the month
A very warm month with the mean temperature 13.3C (+1.8) & [+1.6] of averages, highest since 2008, the second warmest May on record at the station. The mean maximum 17.4C (+2.3) & [+1.5] of averages, also highest since 2008, ranked 7 since 1979. The highest maximum was 28.5C on the 26th and the 25th had 26.5C; there was a spell of 5 days 23 to 27th that reached 20C, or more. Minima temperatures were also above average, the mean 9.2C (+1.3) & [+1.7] was also highest since 2008. The highest minimum 16.0C on the 27th was second highest in May on record here. The lowest minimum 3.9C was on the 9th that also had the lowest grass minimum -0.5C one of the only 2 days having ground frost. Soil temperatures too were above average, at 30 cm 13.9C (+0.8) and 100 cm 12.5C (+0.4).
At Gorwel Heights the mean temperature 14.2C was [+2.6], anomaly based on 1981-2010 MetO Llanfairfechan DataPoint. The mean maximum was 18.3C with the highest 27.9C on the 26th and 10 days had 20C, or more. The mean minimum was 10.1C, the highest 16.6C was on the 27th and the lowest 5.5C on the 10th.
It was a dry month with rainfall of 48.8 mm (67%) & [79%] of averages, least since 2010, ranked 30 in Llansadwrn records since 1928, The wettest day was on the 15th having 17.2 mm. The only other day with 5 mm, or more (-2.6), was on the 12th when 10.2 mm fell. There were 16 (+5) days with no precipitation and 19 (+4.5) dry days. Rain days were 12 (-4.5) and wet days 10 (-2.5). The soil surface was dry on 18 mornings and some cracking was noted where undisturbed. Rainfall at Gorwel Heights was 28.6 mm [47%] of average. The most rain 7.6 mm fell on the 12th. There were 20 dry days; 11 rain days; 9 wet days and only 1 over 5 mm. Wet hour duration was 46 while in Llansadwrn 59 hours were recorded.
It was a very sunny month. At RAF Valley 250.0 h were recorded, (119%) & [129%] of averages, just 0.8 h behind last May 2016. It was the fifth sunniest May on the Anglesey record since 1931..
The spring mean temperature of 10.2C was highest since 2011 and was the second warmest in station records since 1979.
Highest June maximum 29.9C, highest mean minimum 11.8C, rainfall [212%] of 30-y average, Valley sunshine [91%]A month of extreme contrasts, very wet first 10-d, hot day on the 21st, cloudy and dull at the end
The first 10-d were very wet with 105 mm the wettest at this station in 38 years. On the 5th 37.8 mm fell, making it the wettest day, with a further 26.0 mm on the 7th, by the end of the month 143.6 mm had fallen (176% & [212%] of averages. It was the wettest June since 1998 and 5th wettest in Llansadwrn since 1929. Rainfall at Gorwel Heights was 94.4 mm [144%]. In Llansadwrn there were 6 days with no precipitation including 5 consecutive (15-19th) and 13 (-2.5) dry days. Rain days were 17 (+2.5), wet days 14 (+2.5). There were 10 days (+5.0) with 5 mm, or more, continuing the trend for heavier falls of rain seen in recent years. Rain duration was 134 wet hours at Llansadwrn and 124 wet hours at Gorwel Heights. The latter had 15 dry days; 15 rain days; 12 wet days; and 8 days with 5 mm, or more. The wettest day there was also on the 5th with 26.0 mm.
Temperatures were all above average. The mean 15.0C [(+1.1)] was equal highest with 2015 & 2010 since 2006. The mean maximum 18.2C ranked 14 (1979) (+0.7) & [+0.4] of averages with the highest 29.9C on the 21st the highest on record in June. There was one other hot day the 19th with 26.6C and 6 days exceeded 20C with a spell of 5 on 17-21 st The lowest maximum was 12.3C on the 29th, this was 0.5C lower than the 12.8C recorded on 9th May. The mean minimum 11.8C (+1.4) & [+1.8] was highest on record in June with the highest 15.7C on the 21st 4th highest on record. The lowest minimum was 8.8C (+2.6) on the 6th was the highest on record. Temperatures at Gorwel heights were mean maximum 19.5C; mean minimum 12.6C; and mean 16.1C [+1.8]. Highest maximum 30.5C on 21st; lowest maximum 12.4C on 29th. The highest minimum was 16.2C on the 17th and lowest 8.9C on the 6th.
There were 4 consecutive sunless days at RAF Valley at the end of the month (27-30) with another on the 23rd, 5 in all. In Llansadwrn there were 7 sunless days, but we had a little on the 27th! Sunshine was 155.7h lowest since 2012 and ranked 31 on the Anglesey record since 1931. The sunniest day was on the 17th with 15.1h. The mean solar radiation in Llansadwrn was 15.41 MJ m -2 with the highest on the 17th 26.96 MJ m -2 . The lowest 2.92 MJ m -2 was on the 29th. The brightest hour was between 12 and 13 GMT on the 9th with 911 W m -2 .
Sunny with temperatures close averages, wetter than the long term averageWeather was mixed through the month and more like April or October at times
A sunny month the 194.9 h of sunshine recorded at RAF Valley was (103%) & [117%] of averages, highest since 2014 ranking 14th on the Anglesey record since 1931. The sunniest day was on the 17th having 15.3h and there were 2 sunless days. Apart from Jersey that had 215.0 h the sunniest places were around the Irish Sea. The Isle of Man had 211.6 h; Tiree 208.0 h; and Aberdaron 197.0 h. Much was made of the fact in the Press that Lerwick in the Shetland Islands with 184.2 h had more sunshine than Cornwall where Camborne had 135.9 h.
Temperatures in Llansadwrn were very average. The mean maximum 19.4C, highest since 2014 ranked 14th since 1979, the highest maximum 26.6C (+1.0) on the 18th. The mean minimum 12.1C lowest since 2015 ranked 15th, the highest 16.1C on the 19th and lowest 9.1C on the 2nd. The resultant mean 15.7C was (0.1) & [0.0], highest since 2014 rank 18th.
Rainfall was 88.5 mm (88%) & [127%] of averages, lowest since 2015 but one of the 30 largest July falls since 1928. The largest fall was 14.3 mm on the 25th. There were 7 days (-1.9) with no precipitation and 9 (-2.7) dry days. Rain days were 22 (+2.7), wet days 17 (+1.8) and 7 days (0.2) had 5 mm, or more.
All parameters close to the averagesA low number of warm days, rain and sunshine well distributed through the month
Rainfall for the month was 96.0 mm, lowest since 2015, just missing the 100 mm mark of which there have been 37 in Llansadwrn since records began in 1928. Close to the decadal average (96%) and a little above the 30-y average [110%] rain was generally well distributed through the month with no long dry spells. There were 6 days (-1.3) with no precipitation and 13(0.8) dry days. Rain days were 18 (-0.8); wet days 14 (0.7) while 5 (-0.4) days had 5 mm, or more. The wettest day was on the 6th having 35.8 mm; rainfall duration was 86 wet hours. Gorwel Heights had 84.4 mm [100%] with the wettest day on the 6th having 19.0 mm. Dry days were 11; rain days 20; wet days 16; and there were 6 having 5 mm, or more. Rainfall duration was 78 wet hours.
Maximum temperatures were disappointing for the month of August. The highest in Llansadwrn was 23.0C (0.6) on the 22nd and at Gorwel Heights 24.4C on the 27th. There were just 3 days with 20C, or more, in Llansadwrn; Gorwel Heights fared better with 10 days aided by the local microclimate. Highest minima were 14.5C (-0.9) in Llansadwrn and 15.3C at Gorwel Heights each on the 23rd.
With hours of daylight well into the August decline the brightest days were at the beginning of the month. The 9th had 22.41 MJ m -2 of solar radiation and Valley had its sunniest day with 12.9h. In contrast the 11th was a very dull day with just 3.66 MJ m -2 . In total Valley had 175.3 h of sunshine, lowest since 2015, but ranked 22nd highest on the Anglesey record since 1931.
Wettest summer since 2015 [146%] of the 1981 - 2010 climatological average and 13th wettest since 1929. There have been 40 drier summers when the rainfall has been below the 30-y average and 49 wetter summers.
Mostly dull and wet with temperatures a little below average
A wet beginning to the month thereafter mostly dull and damp
After a rather poor summer September was no better. Rainfall was 139.1 mm (144%) & [145%] of averages largest since 2012 following on from four Septembers having less than 100 mm. Ranking 19th since 1928 it was the 41st to have over 100 mm. The wettest September here was in 1935 with 220.7 mm and the driest in 1986 with 11.7 mm. The wettest day of the month was on the 4th with 22.3 mm and another 3 days >10 mm were the 7th 18.0 mm; the 10th 17.5 mm; and the 13th 17.6 mm: 10 (+4.1) days had 5 mm, or more. There were just 4 (-5.5) days without precipitation; 25 (+9.0) rain days; and 20 (+8.3) wet days. Gorwel Heights had 126.4 mm [129%] of the average and a wettest day of 18.6 mm on the 4th. There were 7 dry days; 23 rain days; 17 wet days; and 11 had 5 mm, or more. Rainfall duration was 154 hours in Llansadwrn and 133 hours at Gorwel Heights.
With a large amount of cloud cover there were few warm days and none 20C, or more, in Llansadwrn, where the highest maximum was 19.4C on the 2nd, but at Gorwel Heights there were 4 with the highest maximum 21.7C on the same day. Lowest maxima were on the 16th with 13.3C (+1.2) in Llansadwrn and 13.2C at Gorwel Heights. The mean maximum, lowest since 2015, was 16.5C (-0.2) & [(-0.8] of averages and the mean minimum 10.6C (-0.2) and [+0.3] of averages. The highest minimum were on the 24th with 14.4C in both Llansadwrn and Gorwel Heights. The lowest minima were 8.7C at Gorwel Heights on the 17th and 7.5C in Llansadwrn on the 14th. The lowest grass minimum was 4.3C on the 17th.
Sunshine was at a premium with 113.1 h reported at Valley (85%) & [89%] of averages lowest since 2013. The sunniest day was on the 2nd with 9.1h and there were 5 sunless days. In Llansadwrn solar radiation had a mean of 7.88 MJ m -2 with 9 days seeing 10 MJ m -2 , or more, highest 12.47 MJ m -2 on the 2nd; and 6 days less the 5 MJ m -2 , the lowest was 2.60 MJ m -2 on the 24th a very dull day day with the hour from 1300 GMT having just 62 W m -2 and from 1400 GMT 28 W m -2 . The brightest hour was from 1300 GMT on the 13th with 609 W m -2 .
Mild, wet and very dull
Mild and windy with extra-tropical Ophelia on the 16th and autumnal storm Brian on the 21st
The mean temperature was 12.2C (+0.8) & [+1.3] of the averages highest since 2014 ranking 7th at the station since 1979. The highest means were 17.5C and 17.3C on the 15th and 16th respectively. The mean maximum was 14.8C [(+0.8)] that ranked 8 with the highest maximum 21.7C (+2.3) on the 16th. The lowest maximum was 12.4C on the 30th. The mean minimum was 9.6C (+0.9) & [+1.9] of averages and ranked 7th. The lowest minimum was 3.6C on the 30th that also had the first ground frost of the season -1.2C (-0.9) since 10th May with 172 frost-free days. At Gorwel Heights the mean temperature was 13.1C [+1.5]. The highest maximum was 23.1C on the 15th with 23.5C recorded at Gorddinog equalling the UK highest on the day at Manston in Kent.
Rainfall was 121.1 mm (101%) & [94%] of averages, largest since 2014, but ranking only 42nd since 1928. The largest fall was 23.5 mm on the 24th. There were 4 (-3.7) days with no precipitation and 10 (-1.1) dry days; 21 (+1.1) rain days; 14 (0.0) wet days; and 10 (+2.9) days with 5 mm, or more. Rainfall at Gorwel Heights was 81.4 mm [65%] of average. There the largest fall was 15.2 mm on he 24th and the only other day in double figures was the 21st that had 14.8 mm. Rainfall duration was 119 h (with 1.0 mm/h) and 116 h (0.7 mm/h) at Llansadwrn and Gorwel Heights respectively.
A very dull month with only 60.7 h of sunshine recorded at RAF Valley, (64%) & [62%] of averages lowest since 2011, the 5th lowest on the Anglesey record since 1931. There were 13 sunless days and the sunniest day was on the 5th with 8.7h. Solar radiation in Llansadwrn averages 4.36 MJ m -2 with the brightest day on the 12th with 8.04 MJ m -2 and remarkably the next day the 13th was the dullest with only 0.71 MJ m -2 .
Record daily rainfall total at this station
Somewhat cooler than the decadal average, but close to the 30-y average, Wettest in the second half
Total rainfall was 209.9 mm (164%) & [166%] of averages, largest since 2015 ranking 8th since 1928. The wettest day was on the 22nd with 90.4 mm, a record high any month for this station, but not Llansadwrn. The largest on record is the 127 mm falling in 3 hours, recorded by the late Mr. Dic O'Connor at Treffos, during a thunderstorm on 10 August 1957. The previous day the 21st had 29.2 mm, the two days clocking up 119.6 mm more than half of the month's total. One day, the 2nd, had no precipitation and 6 (-1.6) were dry having <0.2 mm, There were 24 rain days (+1.6) and 19 (+1.4) wet days. There were 9 (+0.7) days that had 5 mm, or more. It was not as wet in Llanfairfechan where 129.2 mm [96%] of average fell at Gorwel Heights. The wettest day, also the 22nd, had 39.8 mm. Rainfall duration was similar at both stations, 147h in Llanfairfechan and 152h in Llansadwrn..
Temperatures were on the cool side compared with those of the late decade and a little below the 30-y climatological average. The mean 7.5C (-1.4) & [-0.2] was highest since 2015, the ranking middle-of-the-road 19th within 39 years records. Maxima were low compared with recent years, the mean maximum 10.1C (-2.0) and [-0.3] of averages, the highest 13.6C on the 1st and the lowest 5.0C on the 30th. The mean minimum 5.0C was equal to the 30-y average and below (-0.7) the decadal. The lowest minimum was 0.7C on the 25th which also hosted the lowest grass minimum of -4.2C. There were 14 days with ground frost (+6.8) equal lowest (3 years) since 1993. At Gorwel Heights the mean temperature was 8.3C [-0.6]. The highest maximum was 14.6C on the 1st and the lowest 5.3C on the 30th. The lowest minimum was 2.3C on the 25th and the highest 12.3C on the 21st.
Some strong winds on the 22nd. At Gorwel Heights there was a gust of 64 mph and a mean wind speed of 11.1 mph. In Llansadwrn there was a gust of 44 mph and a mean wind speed of 14.0 mph. Over the 4 days 20-23rd there was an impressive wind run of 870 miles with 300 miles recorded on the 22nd.
There were 8 days of hail (+1.9), most since 2012.
Last autumn was the driest for over 60-years with rainfall 66% of the 30-y average, this autumn was rather wetter having 470.1 mm, ranking 9th in Llansadwrn records since 1928, wettest since 2008. Autumn is the wettest season here with 21 having 400 mm, or more, winter has 11, summer 2 and spring none. It falls short, however, by 142 mm of the 612.1 mm recorded in autumn 2000 that went on to be the wettest year recorded in Llansadwrn. This had 1483.9 mm, 333.5 mm more than the 1150.4 mm in 2017 so far. A very wet December, like 2015 that had 415.8 mm, could break that record.
Coolest since 2015, but 15th warmest in station records since 1979. Average temperatures were very similar to autumn 2016
Drier than average with mean temperatures just above averages
A cold spell before the end of the first half, otherwise mild with brief wet and windy weather
The predominate wind direction was south-westerly and although the rainfall for the month was > 100 mm, the total of 115.6 mm (74)% of the decadal average and largest since 2015 it was closer to the 30-y average at [96%] ranking 44th largest in Llansadwrn since 1928. There were two wet days; the 6th having 18.7 mm and the month's largest 21.8C on Christmas Day the 25th. It was a damp month with nil (-4.6) days with no precipitation; 2 (-6.9) days (<0.2 mm); 29 (+6.9) rain days and 19 (+1.1) wet days. There were 8 (-1.8) days that had 5 mm, or more. Rainfall duration was 113 h.
The mean temperature was 5.9C (+0.1) & [+0.5] of averages, lowest since 2012 ranking 19th lowest since at this station since before 1979. The highest maximum, about average, on the 6th was 12.3C and the lowest 1.2C (-2.9) was on the 10th. The highest minimum was 9.4C on the 25th and the lowest -1.1C (+0.4) on the 11th. There were 5 days (+0.6) of air frost amounting to 21.3 h below zero, none last December and this number exceeding last year's total by one. There were 13 (-3.0) ground frosts, the same as in 2016, the lowest -6.9C was also on the 11th.
Rainfall at Gorwel Heights was 96.6 mm [74%], largest fall 23.4 mm on the 25th. There were 3 dry days; 28 rain days; 17 wet days; and 6 had 5 mm, or more. Rainfall duration was 147 h. The mean temperature was 11.5C [+0.8]; the highest maximum 13.8C on the 6th and lowest 1.7C on the 10th. The highest minimum was 10.6C on the 20th and the lowest -1.1C on the 11th and 12th. There were 13.3 h duration of frost.
Sunshine was at a premium again in December. At RAF Valley sunshine was 34.5 h (79%) & [73%] of averages. The sunniest day was on the 1st with 5.8h and there were 15 sunless days the highest monthly total of the year. The mean solar radiation on Llansadwrn was 1.87 MJ m -2 , the highest 3.54 MJ m -2 on the 1st and lowest 0.69 MJ m -2 on a dull Christmas Day.
Warmest since 2014 and wettest since 2015
The Met Office at RAF Valley kindly supplied observational data from 1942 to 2011. Current data (provisional) are gathered from SYNOP reports and METAR. I am grateful to David Lee for use of data from Gorddinog..