Davis Vantage Vue AWS at Gorwel Heights in Llanfairfechan.

Llansadwrn (Anglesey) Weather:
Monthly and Annual
Summary for 2020

Logo: Llansadwrn Weather - Melin Llynnon, Ynys Môn




January 2020

Wet, windy, mild and dull: Rainfall and temperatures well above averages, rather dull.

The beginning was very mild, wet and windy, The end was more wintry and unusually foggy at times.

Rainfall totalled 154.2 mm (158%) & [151%] of averages, largest since 2016 and ranked the 13th wettest Decembers in Llansadwrn since 1928. The wettest day and raining for 18 hours was on the 11th having 32.5 mm, other wet days were the 8th with 16.0 mm and the 16th with 24.2 mm. Despite the wet days there were 3 (-1.0) that had no precipitation, dry days (having <0.2 mm) numbered 7 (-1.6). Rain days (>=0.2 mm) were 24 (1.6); wet days (>=1.0 mm) were 16 (-0.9); and days that had 5 mm, or more, 10 (3.0). Rainfall duration (wet hours) was 138 and the average rainfall per hour was 1.1 mm.

Rainfall at Gorwel Heights was 126.0 mm [111%] with the wettest day on the 11th with 30.2 mm. There were 11 dry days; 20 rain days; 14 wet days and 7 had 5 mm, or more. Wet hours were 98 less than Llansadwrn, but the average rate of fall was 1.3 mm/h was greater.

Temperatures were well above averages. The mean temperature at Llansadwrn was 6.4C (1.1) & [1.3] of averages, highest since 2016. The mean maximum 8.7C (1.0) & [1.1] was highest since 2016 and ranked 6th in station records since 1979. The highest maximum was 11.6C on the 7th (-0.2) closely followed by the 11.5C recorded on the 7th. The lowest maximum was 5.5C on the 9th. The mean minimum was 4.0C (1.2) & [1.4] highest since 2008 ranked 8th. The lowest minimum on the 18th was -0.2C (1.8) the only day with air frost, but that lasted for only 0.5h. There were, however, 14 (-4.0) days with ground frost equal lowest with 2016/17 since 2008, the lowest -4.5C (2.2) on the 18th. The warmth was reflected also in the soil temperatures: the mean at 30 cm 6.4C (1.0) and at 100 cm 7.9C (0.6).

Temperatures at Gorwel Heights in the Llanfairfechan microclimate were remarkable for January. The mean 7.6C 1.2 degrees higher than Llansadwrn had an anomaly of [1.4] based on 1981-2010 Met Office Llanfairfechan DataPoint. The mean maximum was 10.0C with 16 days in the month of 10C, or more. A record Föhn-enhanced maximum of 16.9C at Gorddinog and 17.4C was recorded in Llanfairfechan at 1250 GMT on the 7th at Gorwel Heights both stations beating the previous highest 15.0C recorded on this date at Rhyl in 1934 and at St. Abbs Head in 1989 (TORRO). The lowest maximum was 5.5C on the 28th. The mean minimum at Gorwel Heights was 5.2C, the highest 8.5C on the 31st and the, lowest 1.8C on the 28th there being no air frost recorded.

The wind direction was predominately SW'ly 15 days in Llansadwrn and 18 days at Gorwel Heights. No snow was seen in Llansadwrn, but there were 6 days when small hail (snow pellets and ice pellets) were recorded. Sunshine at RAF Valley was 48.0h (90%) & [83%] ranked 32nd lowest on the Anglesey record since 1931. The sunniest days was on the 16th and 20th with 6.1h. There were 15 sunless days

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February 2020

Wettest February on record in Llansadwrn, temperatures lowest since 2018, but mean 12th warmest over past 43-years.

Stormy and wet throughout occasionally wintry.

Rainfall this month was 250.6 mm the largest in Llansadwrn February records back to 1928, (304%) & [319%] of averages. The largest fall was 55.3 mm on the 8th; 42.0 mm on the 19th; 28.6 mm on the 15th; 25.4 mm on the 22nd; and 23.3 mm on the 28th There was one day (-4.3) on the 6th that had no precipitation; 4 dry days (-5.8); 25 raindays (+6.6); 17 wet days (+4.5); and 10 days with 5 mm, or more (+4.5). Four days had 25 mm (1 inch), or more. There were 166h (wet) rainfall duration, the 19th had 20h of them, the 7th and 15th each 16h, the 21st 15h, the 28th 14h, all thoroughly wet days. The average rain falling per hour was 1.5 mm. Rainfall at Gorwel Heights, Llanfairfechan was a little less at 240.2 mm, largest in February and [309%] of MetO DataPoint average. The largest fall was 37 mm on the 7th with 35.4 mm on the 15th. There were 4 dry days; 25 Rain days; 21 wet days; and 9 days had 5 mm, or more. Five days had 25 mm (1 inch), or more. There were 181 wet hours duration with an average 1.3 mm/h. Rainfall at David Lee's station at Gorddinog was largest of the three stations with 285.4 mm, the largest fall 48.9 mm on the 8th.

Temperatures were above average. The mean temperature 6.3C (+0.7) & [+1.1] of averages while lowest since 2018 was nevertheless 7th warmest over 42-years records. The mean maximum 8.8C (+0.3) & [+0.5] smallest of the anomalies. The highest maximum 11.4C on the 7th and 9th, the lowest 5.9C on the 11th. The mean minimum 3.8C (+1.1) & [+1.6] of averages. The highest 7.3C on the 1st and the lowest 0.4C on the 7th. There was no air frost, but there were 16 days of ground frost. The lowest was -3.8C on the 7th. At Gorwel Heights the mean temperature was 6.8C [+0.9] of average. The mean maximum was 9.2C with the highest 13.1C on the 7th and the lowest 5.2C on the 11th. The mean minimum was 4.4C with the highest 8.2C on the 15th and lowest 2.4C on the 11th and 26th. The highest maximum recorded at Gorddinog was 13.6C on the 7th.

Some high gusts were recorded. At Gorwel Heights on the 8th 85 mph; 63 mph on the 9th; and 66 mph on the 15th. At Llansadwrn 57 mph was recorded on the 9th; 50 mph on the 15th; and 52 mph on the 29th.

Winter 2019/20

Largest winter rainfall since 2016, third wettest since 1928. Temperatures lowest since 2018, but the mean 6.5C ranked 7th warmest over the past 42-years

Winter seasonal averages Anomalies
10-y 30-y
Temperature (C)
Mean maximum 8.8 +0.5 +0.9
Mean minimum 4.1 +0.9 +1.5
Mean 6.5 +0.7 +1.2
Rainfall (mm) 505.7 162% 168%

 

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March 2020

Near average rainfall and temperatures hides the true picture.

Wet and cold beginning, dry, very sunny and warmer end.

Rainfall of 85.7 mm (104%) and [101%] of averages, lowest since 2016, but ranking 29th largest since 1928, hid the fact that the last 14 days had no significant rain, 12 days were perfectly dry. The largest fall was on the 17th having 22.2 mm. Days with no precipitation were 13 (+5.8); dry days were 16 (+3.0); rain days 15 (-3.0); wet days 10 (-4.6); and days with 5 mm, or more, 5 (-3.4).

Rainfall at Gorwel Heights was 78.4 mm [91%] of average. The largest fall was 29.8 mm on the 17th. Dry days wee 18; rain days 13; wet days 9; and there were 5 days that at 5 mm, or more.

The mean temperature was 7.0C (+0.2) & [0.0] of averages, lowest since 2018, ranking 19th lowest in station records since 1979. The mean maximum 10.4C ranked even lower 24th, the highest maximum 18.1C on the 25th stood out in the month. The lowest maximum was 6.6C on the 18th. The mean minimum was 3.5C and the lowest minimum 0.2C on the 2nd so no air frosts. The lowest grass minimum was -5.0C on the 2nd and there were 13 ground frosts.

At Gorwel heights the mean temperature was 7.6C [+0.2] of average. The mean maximum was 10.6C with the highest 17.6C on the 24th. The mean minimum was 4.6C with the lowest minimum 2.0C on the 6th.

 

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April 2020

Very sunny, warmest since 2011 and driest since 2010.

Only two cool sub 10C days 1st and 28th, wettest at the end of the month, 28th only sunless day.

Sunny. Sunshine recorded at RAF Valley was 215.8h most since 2015 that was the sunniest April on the Anglesey record back to 1931. This year ranked the 5th sunniest. Two sunniest days the 20th and 21st each 13.0h. The 28th was the only sunless day.

Until the 17th there had only been 1.9 mm of rain and it looked as if the month was challenging the record low of 6.7 mm here in 1980 the second year of observations at the station. This was not to happen as 7.2 mm fell on the 17th, a fall not seen in Llanfairfechan (GH) where only 3.8 mm had fallen by the 27th, and a wet end to the month brought the total up to 25.1 mm here and 23.4 mm at Gorwel Heights. The 25.4 mm was (47%) &[40%] of averages ranked 9th lowest in Llansadwrn since 1928. There was no precipitation on 20 days (+8.7); and there were 22 dry (< 0.2 mm) days (+7.8). Rain days were 8 (-7.8); wet days 5 (-6.1); and just 2 days (-4.2) with 5 mm, or more. The wettest day was on the 29th with 7.8 mm. Rainfall at Gorwel Heights 23.4 mm was [37%] of average with the most 12.8 mm falling on the 29th. There were 22 dry days; 8 rain days; 5 wet days and only 1 had 5 mm, or more. Rainfall duration (wet hours) was 37 at Llansadwrn and 34 at Gorwel Heights.

Soil moisture under grass (2-8 cm) determined on the 21st was 39.1% dry mass down from 43.8% dm on the 8th. The top 2 cm consisting of mainly compacted roots and grass containing most of the moisture was 46% dm, down from 69% dm on the 8th. On the undisturbed met plot 0-8 cm deep was 15.2%, similar to that at the beginning o the month. On the vegetable plot, that has a larger organic matter content (not irrigated), 0-8 cm was 20.7% dm and 8-14 cm was 24.5% dm. The permanent wilting percentage for the soil here is 15% dm. We have had a very dry event. It is remarkable that this situation arose so quickly after the wet months of February and March, this is not only due to having had just 8.8 mm by the 21st, but also above average temperatures and high evaporation rates. The month ended with a PE (Potential Evaporation) of 106.7 mm and a calculated ET of 71.0 mm The PWB (Potential Water Balance] by lysimeter was -81 6 mm.

The mean temperature 11.1C (+1.9) & [2.2] of averages highest since 2011 was the third highest in station records. The mean maximum 15.5C (+2.5) & [+2.6] of averages was the second highest. Highest maximum on the 10th was 22.4C (+3.0) was lowest since 2017, but ranked sixth highest. The mean minimum 6.7C (+1.3) & [+1.8] of averages ranked fourth with the lowest 1.5C on the 14th. There was one ground frost of -1.4C on the 14th. At Gorwel Heights the mean temperature was 11.5C [+2.7] with the highest on the 5th was 21.9C. The mean minimum was 7.6C with the highest on the 10th 11.9C and the lowest on the 14th 3.2C.

 

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May 2020

Driest and sunniest May on record.

Remarkably dry and sunny after wet winter. Temperatures above average.

With just 11.9 mm of rainfall it was the driest May in Llansadwrn since before 1928 when records began. Just (17%) & [19%] of averages we had 22 (+10.1) days with no precipitation what so ever. Dry days were 26 (+10.6); rain days only 5 (-10.6); wet days 3 (-7.6) and just one day with 5 mm, or more, in fact the only day 5.8 mm on the 21st. It was even drier in Llanfairfechan where at Gorwel Heights just 7.8 mm were recorded [xx]. The largest fall was 4.8 mm on the 21st.

Sunshine at RAF Valley 312.3h broke all Anglesey records for ANY month back to 1931. With just one sunless day the sunniest day was on the 30th having 15.1h. The previous sunniest May was 271.9h in 2010 and the previous sunniest month was July 2013 with 211.4h.

We had two hot days on the 29th with 25.3C and 25.4C on the 30th not quite getting three to call it a heatwave as the 30th had 22.6C and the 28th 23.2C. The mean maximum was 17.1C (+1.8) & [+1.2] of averages; the mean minimum 2.2C (+.3) & [+0.7] of averages; and the mean 12.7C (+1.1) & [+0.9] of averages, highest since 2017 ranking 7th warmest over the last 40 years. The lowest minimum was 2.0C on the 12th that also had the lowest grass minimum -2.7C. There were 3 days of ground frosts (+1.6). At Gorwel Heights the highest maximum was 24.7C on both the 29th and 30th with highest minima 15.6C on both the 30th and 31st.

Spring 2020

Spring rainfall anomalies at Llansadwrn since 1929.A very dry April and May meant that the rainfall total 122.7 mm was fourth driest on record in Llansadwrn since before 1928. Drier springs were 1990 with 80.2 mm, 1984 with 110.7 mm, and 1974 99.6 mm. Temperatures were above the averages and the mean 10.2C was second highest on record only beaten by 2011 that had a mean just 0.2C higher at 10.4C. It was the sunniest spring on record on Anglesey since before 1931. Sunshine recorded at RAF Valley totalled 682.1h beating 2010 that had 641.8h the only other >600h spring.

 

Spring seasonal averages Anomalies
10-y 30-y
Temperature (C)
Mean maximum 14.3 +1.6 +1.3
Mean minimum 6.1 +0.5 +0.8
Mean 10.2 +1.0 +1.0
Rainfall (mm) 122.7 60% 58%

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June 2020

A dull and wet month with temperatures a little above average. A record 31.3C.

Thundery mid and end of the month.

A record temperature for June of 31.3C was recorded on the 25th with means a little above average. The monthly mean was 14.7C (+0.5) & [+0.8] of averages, highest since 2018 and 12th in the record book since 1979. The mean maximum was 18.2C [(+0.4)] and the mean minimum 11.3C (+0.6) & [+1.3] of averages, the highest minimum was 16.4 on the 26th and the lowest 5.9C on the 8th that also had the lowest grass minimum of 1.8C (-1.5). The earth 30 cm depth average was 15.7C (-0.2) and the 100 cm 14.4C on the button (0.0). At Gorwel Heights the mean temperature was 15.1C [+0.9]. The highest maximum was 30.1C on the 25th and the lowest 11.6C on the 3rd. The mean minimum was 11.9C, the highest minimum was 17.3 on the 26th and the lowest 6.7C on the 6th.

A wet month. Rainfall at Llansadwrn was 102.4 mm (133%) & [151%] of averages, largest since 2017 and ranking 19th in records back to 1929. The wettest day was on the 14th with 14.4 mm. There were 3 days (-9.5) with no precipitation; dry days were 8 (-8.0); rain days 22 (+8.0); wet days 17 (+6.4) and days with 5 mm, or more, significantly 8 (+3.4) the trend being upward in recent years. Wetter at Gorwel heights where 118.4 mm fell [181%] of local average. The wettest day was on the 28th when 19.2 mm fell. Dry days were 9; rain days 21; wet days 18 and days with 5 mm, or more, significantly 9.

It was an unusually thundery month with 7 days of storms observed often with vivid lightning, the 14-17th and 25-27th inclusive.

A rather dull month with 137.6 h of sunshine recorded at RAF Valley, lowest since 2002 and 9th lowest in June on the Anglesey record back to 1931. The sunniest day was on the 1st having 15.5h sunshine. There were just 6 days with 10h, or more, there was one sunless day, but 10 saw less than 1h each day.


July 2020

Wettest since 2010 and 2nd wettest July on record in Llansadwrn since 1928; coolest since 2012 rank 7th in station records since 1979; dullest since 2012 at Valley rank 17th on Anglesey record since 1931.

Pretty wet throughout with one temperature spike on the 31st, absence of thunder

A soaker of month the 179.6 mm (205%) & [257%] of averages, wettest since 2010 with 182.1 mm the largest in July in 92-year Llansadwrn records back to 1928. The largest fall was 35.5 mm on the 3rd, most in a July day since 1988 (36.8 mm on the 28th) ranking second, and the 31st largest overall out of 14960 daily records. Rainfall in Julys in Llansadwrn, Anglesey records back to 1928.There were 5 days (-4.9) with no precipitation and 7 dry days (-6.0); 24 rain days (+6.0); 18 wet days (+4.5); and significantly 13 days had 5 mm, or more, a trend associated with climate heating. Rainfall at Gorwel Heights totalled 128.2 mm, the largest fall in July since 2012 (142.1 mm). Most was on the 8th with 20.0 mm; dry days were 7; rain days were 24; wet days 18; and 9 had 5 mm, or more.

A somewhat cool month for July with a mean temperature 14.6C, lowest since 2012, and ranking 7th lowest in station records since 1979. The mean maximum was 17.6C (-1.8) & [-1.9] of averages, if it was not for the last 2 days the maximum would have been 19.4C on the 24th, but just in time we had 27.4C (-0.9) on the 31st and the 30th was credited with 25.7C as it occurred at 0900 GMT. Low maxima occurred on the 17th and 27th each 13.8C (-0.9). The mean minimum was 11.7C (-1.3) & [-1.1] of averages, the lowest was a cool 7.8C (-1.1) on the 10th that also had a 4.4C grass minimum only to be outdone the next day the 11th with 3.8C and heavy dew.

A rather dull month overall. Sunshine at RAF Valley totalled 128.1h (provisional) least since 2012. It was the 17th dullest July on the Anglesey record. Anglesey sunshine in July's records back to 1931.Lower than average sunshine totals are not unexpected in July more's the pity (graphic left), really sunny Julys with 50 hours anomaly, or more, with ten are rather rare. Only 4 days had 10h, or more, the 10th had 10.0h; 11th had 12.4h; the 19th 13.1h was the sunniest; and the 20th 12.2h. Fourteen days saw 1.0h, or less, of which 7 were sunless. Llansadwrn had 10 sunless days with the lowest solar radiation 3.51 MJ m -2 seen on the 3rd when the light level in the hour from noon was only 62 W m -2 in comparison to the brightest 824 W m -2 on the 19th which was also the brightest day with a total of 23.52 MJ m -2 .

The month was notable for the absence of thunder and hail, and its number of foggy days 7 when the island was often enveloped in low cloud when bright and sunny in Llanfairfechan...


August 2020

Wettest August in Llansadwrn since 1961 and 4th wettest August on record since 1928; warmest since 2004 ranking 8th in station records since 1979; dullest since 2018 at Valley ranking 40th on Anglesey record since 1931.

Wet at times throughout, turned cooler at the end, record low 2.5C grass minimum. Four days with thunder, but no hail observed.

A very wet month with 168.5 mm of rainfall (183%) & [194%] of averages. Largest in August since 1961 and ranking 4th in Llansadwrn records back to 1928. Llansadwrn rainfall in 1961 was 190.8 mm at Treffos and 180.1 mm at Gadlys Cottage, but the largest was in 1957 when 230.4 mm fell at Gadlys Cottage and 218.4 at Treffos. The largest daily falls this August were 39.0 mm on the 25th, 29.2 on the 17th and 23.5 mm on the 4th. There were, however, 7 days (-0.4) with no precipitation and 9 days (-3.1) dry days. Rain days were 22 (+3.1); wet days 16 (+2.7); and 7 days (+2.4) having 5 mm, or more. Rainfall at Gorwel Heights was larger with 193.6 mm [229%] with 42.2 mm falling on the 25th over 13h duration, and 26.2 mm falling on the 10th during a thunderstorm over the Carneddau and Llanfairfechan with torrential rain at 1450 GMT at Gorwel Heights, 19.2 mm falling in 20 minutes with 24.4 mm in total during the 1 hour event from 1440-1540 GMT and a 24-h total of 26.2 mm over 4h duration. The Aber road out Llanfairfechan was flash flooded and some road surfaces damaged. Gorddinog AWS reported no rain in that hour, but had less intense rain earlier and later with a total of (17.2 mm). Gorwel Heights had 11 dry days; 20 rain days; 16 wet days; and 11 with 5 mm, or more. Rainfall duration for the moth (wet hours) were 130h in Llansadwrn and 124 in Gorwel.

It was a generally warm month, the mean in Llansadwrn was 16.4C (+1.2) & [+0.8] of averages, equal highest with 2019 since 2004, but off the absolute highest mean 18.7C in 1995. The mean maximum was 19.4C, equal to 2019 and 2016, highest since 2005 (19.8C). There were 12 warm days (>=20C) with a spell of 9 days 7-15th all in the first 20 days. The highest maximum was 25.5C on the 11th, the only hot day, but two days reached 24.9C and 24.8C on the 12th and 13th. The lowest maximum was 14.7C on the 27th this reflecting the cooler last 11 days. The mean minimum was 13.3C (+1.1) & [+1.3] of averages, the lowest 6.9C (-1.2) on the 31st, reflecting the rather chilly unseasonable end to the month, equal lowest with 2014 since 1993 (6.5C). The lowest grass minimum 2.5C also occurred on the 31st, the lowest on record in August at this station. At Gorwel Heights the mean temperature was 17.2C [+1.0] of average. The mean maximum was 20.2C with the highest 26.9C on the 13th with 3 other hot days on the 7th 25.3C; 12th 25.6C; and 14th 25.0C. There were 15 warm days (>=20C) with a spell of 12 days 4-15th. The lowest maximum was 14.1C on the 29th. The mean minimum was 14.1C with the lowest 9.1C on the 31st.

Thunderstorms occurred on 4 days, 10th, 11th, 12th and 21st, but no hail was observed in the month.

It was a dull month overall with 155 hours of sunshine and 5 sunless days recorded at RAF Valley. The sunniest day was on the 8th with 13.6h followed by 12.6h on the 9th. Overall there were 6 days with 10h, or more.

In Llansadwrn the mean solar radiation was 12.20 MJ m -2. with the highest 22.3 MJ m -2 recorded on the 9th and the lowest 3.64 MJ m -2. on the 25th. The brightest hour up to noon on the 15th received 547 W m -2.

 


Summer 2020

Wet and dull, mean temperature a little above average

Summer rainfall anomalies at Llansadwrn since 1929.The 450.5 mm of rainfall, (176% & [202%] of averages, made it the wettest summer in Llansadwrn since records began in 1928

The mean summer temperature 15.3C was lowest since the 16.4C in 2018, but ranked 14th highest in 42-years of station records.

After the sunniest spring on record it was the dullest summer since 2004. Sunshine at RAF Valley was 420.7h (provisional), (71%) & [64%] of averages, ranking 14 on the Anglesey record since 1931.

Summer seasonal averages Anomalies
10-y 30-y
Temperature (C)
Mean maximum 18.4 0.0 -0.4
Mean minimum 12.1 0.3 0.8
Mean 15.3 0.2 0.2
Rainfall (mm) ....... Record 450.5 176% 201%

 


Monthly data 2020

Llansadwrn (Anglesey): Monthly weather data summary for 2020
Anomaly ~ is based on the 2010-19 average.
Anomaly 30-y is based on the 1981-2010 average.
.
.
Air temperatures (C) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
.
Mean max 8.7 8.8 10.4 15.5 17.1 18.2 17.6 19.4 14.5
Mean min 4.0 3.8 3.5 6.7 8.2 11.3 11.7 13.3 7.8
Mean 6.4 6.3 7.0 11.1 12.7 14.8 14.6 16.4 11.1
Anomaly~ 1.1 0.5 0.2 1.9 1.1 0.5 -1.3 1.2 0.2
Anomaly 30-y 1.3 1.1 0.0 2.2 0.9 0.8 -1.1 0.8 0.4
High max 11.6 11.4 18.1 22.4 25.4 31.3 27.4 25.5 31.3
Date 16 7 25 10 30 25 31 11 .
Low max 5.5 5.9 6.7 8.6 10.4 12.1 13.8 14.7 5.5
Date 9 11 18 28 11 3 17, 27 27 .
High min 7.0 7.2 6.8 11.5 13.9 16.4 14.8 18.3 18.3
Date 6 1 17 10 31 26 31 13 .
Low min -0.2 0.4 0.2 1.5 2.0 5.9 7.8 6.9 -0.2
Date 18 7 2 14 12 8 10 31 .
Grass min -4.5 -3.8 -5.0 -1.4 -2.7 1.8 3.8 2.5 -5.0
Date 18 7 2 14 12 8 11 31 .
.
MSL Pressure at 09 GMT (mb) 1017 1005 1017 1018 1022 1012 1016 1011 1015
Highest 1049 1039 1046 1031 1038 1026 1029 1024 1049
Date 20 5 29 14 27 1 12 8 .
Lowest 978.7 972.1 979.0 986.9 993.8 996 996 983 972.1
Date 14 9 1 30 1 6 27 25 .
.
Means at 0900 GMT .
Air temperature (C) 6.1 5.9 6.8 11.4 13.4 15.0 14.6 16.2 11.2
Dew point (C) 4.5 3.6 3.8 6.8 8.4 12.0 12.4 14.5 8.3
RH% 90 86 82 74 73 83 87 90 83
Soil temperatures (C) .
.
5 cm 5.4 5.2 6.3 11.9 15.2 16.7 16.3 17.5 11.8
10 cm 5.7 5.5 6.1 10.6 12.9 15.3 15.5 16.9 11.1
20 cm 5.8 5.8 6.8 10.9 13.2 15.7 15.9 17.5 11.5
30 cm 6.4 6.4 7.4 11.3 13.3 15.7 16.1 17.7 11.8
Anomaly~ 1.0 1.0 0.3 1.2 0.3 -0.2 -1.2 0.7 0.6
50 cm 7.0 6.9 7.7 11.2 13.1 15.4 15.9 17.4 11.8
100 cm 7.9 7.6 8.1 10.6 12.4 14.4 15.2 16.5 11.6
Anomaly~ 0.6 0.8 0.4 0.8 0.4 -0.0 -0.6 0.3 0.1
.
Rainfall (mm) .
.
Rain tot 154.2 250.6 85.7 25.1 11.9 102.4 179.6 168.5 978.0
Rain % ave~ 158 3.4 104 47 17 133 205 183 85
Rain % 30-y 151 319 101 40 19 151 257 194 90
Days 0.0 3 1 13 20 22 3 5 7 74
Days <0.2 7 4 16 22 26 8 7 9 99
Days >=0.2 24 25 15 8 5 22 24 22 145
Days >=1.0 16 17 10 5 3 17 18 16 102
Days >=5.0 10 10 5 2 1 8 13 7 56
Max fall 32.5 55.3 22.2 7.8 5.8 14.4 35.5 39.0 55.3
Date 11 8 17 29 21 14 3 25 .
Highest rate (mm/h) 70 60 20 18 19 75 37 175 175
Date 16 8 14 17 21 14 27 20 .
Average rain per hour (mm) 1.1 1.5 1.1 0.7 0.8 0.8 1.1 1.3 1.2
.
Evaporation .
.
Piche (mls/ mm) 27.7 37.0 43.3 57.8 76.9 41.4 36.5 71.3 391.9
Lysimeter PE (mm) 32.6 39.1 57.8 106.7 150.8 88.6 77.9 61.9 615.4
AWS ET calculated 18.6 40.7 48.4 71.0 92.9 60.8 54.0 55.7 442.1
.
Weather (days) .
.
Air frost 1 0 0 0 0 0 0 0 1
Ground fr 14 16 13 1 3 0 0 0 47
Sl/snow 0 1 0 0 0 0 0 0 1
Sn lying 0 0 0 0 0 0 0 0 0
Thunder 0 1 0 0 0 7 0 4 12
Hail <5 mm 6 13 3 0 0 0 0 0 22
Hail >=5 mm 0 1 1 0 0 0 0 0 2
Fog at 09h 2 0 1 0 0 0 0 0 3
Gales in SE Anglesey 5 6 0 0 1 0 0 3 15
.
Wind direction at 09h (days) .
.
N 0 1 3 2 3 3 2 1 15
NE 0 0 3 6 9 7 2 6 33
E 1 0 4 6 1 1 0 5 18
SE 2 1 3 4 2 0 0 1 13
S 5 4 3 4 6 5 7 3 37
SW 15 11 10 7 6 9 12 11 81
W 6 9 4 1 3 4 4 3 34
NW 0 3 1 0 1 1 3 1 10
Calm 2 0 0 0 0 0 1 0 3
.
Wind speed mph .
.
Daily mean 8.8 11.4 8.0 3.7 4.4 4.4 4.9 4.8 6.3
Highest daily mean 18.3 22.3 16.6 10.1 17.1 14.3 12.9 16.2 22.3
Date 7 21 7 6 22 28 3 21 .
Mean gust 26.0 33.7 23.9 15.0 15.5 15.9 18.3 18.0 20.8
Highest gust 53 57 41 33 42 32 39 46 57
Date 13 9 11 6 22 21 4 21 .
.
AWS records of rainfall and frost .
.
Wet hours (with 0.2 mm,or more) 138 166 78 37 15 129 162 1130 855
Frost duration (h) 0.5 0 0 0 0 0 0 0 0.5
.
Cloud cover at 09h. Mean % 75 84 73 63 58 83 85 77 75
.
Global solar radiation (MJ m-2) .
.
Llansadwrn
Sol rad mean 2.38 4.84 10.16 16.20 20.89 13.76 12.02 12.20 11.56
Maximum 4.80 9.42 18.60 23.92 28.44 28.00 23.52 22.30 28.44
Date 20 26, 29 31 27 17 1 19 9 .
Minimum 0.53 0.92 2.84 5.15 3.28 3.84 3.51 3.88 0.53
Date 11 15 7 28 20 29 3 17 .
Brightest hour W/sq m 271 374 733 815 862 853 824 847 862
during hour beginning GMT 12 12 12 11 12 12 12 11 12
on day 20 29 31 28 11 1 19 15 .
Sunless days 14 5 4 1 2 1 10 7 44
.
Sunshine (h) .
[ ~ missing days are derived] ~ 5 .
Valley 48.0 77.8 154.0 215.8 312.3 137.6 128.1 155 1228.6
Average %~ 90 94 118 122 146 62 64 91 78
Average 30-y 83 97 136 137 161 80 77 96 86
Sunniest 6.1 8.7 11.5 13.0 15.1 15.5 13.1 13.6 15.5
Date 20 27 27 20, 21 30 1 19 18 .
Sunless days 15 5 2 1 1 1 7 5 37
.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year

Llanfairfechan, Gorwel Heights observations

Gorwel Heights (73 m), Llanfairfechan (Conwy): Monthly weather data summary 2020
# Anomalies based on 1981-2010 MetO Llanfairfechan DataPoint
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
Air temperatures (C)
.
Mean max 10.0 9.2 10.6 15.4 17.2 18.3 18.2 20.2 14.9
Mean min 5.2 4.4 4.6 7.6 9.5 11.9 12.4 14.1 8.7
Mean 7.6 6.8 7.6 11.5 13.4 15.1 15.3 17.2 11.8
Anomaly [1981-2010] # 1.4 0.9 0.2 2.5 1.8 0.9 -0.8 1.0 1.2
.
High max 17.4 13.1 17.6 21.9 24.7 30.1 28.7 26.9 30.1
Date 7 7 24 5 29, 30 25 31 13 .
Low max 5.5 5.2 6.7 8.8 9.6 11.6 13.1 14.1 5.2
Date 28 11 29 1 11 3 9 29 .
High min 8.5 8.2 7.4 11.9 15.6 17.3 16.1 18.1 18.1
Date 31 15 25 10 30, 31 26 31 13 .
Low min 1.8 2.4 2.0 3.2 4.4 6.7 9.8 9.1 1.8
Date 28 11, 26 6 14 11, 12 6 10, 20 31 .
.
MSL Pressure at 09 GMT (mb) 1016.6 1005 1017 1018 1022 1012 1015 1011 1015
.
Highest 1048.9 1039 1046 1031 1038 1026 1029 1024 1049
Date 20 5 29 14 27 1 12 8 .
Lowest 978.4 972.3 979 987 994 996 995 982 972
Date 14 9 1 30 1 6 27 25 .
.
Means at 0900 GMT
Air temperature (C) 7.3 6.6 7.4 11.4 13.8 15.4 15.0 17.1 9.5
Dew point (C) 4.3 3.2 3.0 6.4 7.8 10.4 10.5 12.6 41.0
RH% 81 80 75 72 68 72 75 75 75
.
Rainfall (mm)
.
Total 126.0 240.2 78.4 23.4 7.4 118.4 128.2 193.6 915.6
% [1981-2010] # 111 309 91 37 12 181 218 229 83
.
Max fall 30.2 37.0 29.8 12.8 4.8 19.2 20.0 42.2 42.2
Date 11 8 17 29 21 28 8 25 .
Highest rate (mm/h) 53 41 20 11 25 111 29 262 262
Date 13 19 12 30 20 25 27 10 .
.
Wet hours (with 0.2 mm, or more) 98 181 70 34 7 120 147 124 781
Average rain per hour (mm) 1.3 1.3 1.1 0.7 1.1 1.0 0.9 1.6 1.2
.
Days <0.2 11 4 18 22 28 9 7 11 110
Rain >=0.2 20 25 13 8 3 21 24 20 134
Wet >=1.0 14 21 9 5 2 18 18 16 103
Days >=5.0 7 9 5 1 0 9 9 11 51
.
Weather (days) .
.
Air frost 0 0 0 0 0 0 0 0 0
Frost duration (h) 0 0 0 0 0 0 0 0 0
Wind direction at 09h (days) .
.
N 1 0 3 7 5 4 5 25
NE 0 1 5 3 2 3 2 16
E 0 0 3 0 3 3 1 10
SE 2 2 2 8 3 3 0 20
S 6 10 8 4 6 5 9 48
SW 18 11 6 3 3 2 6 49
W 1 4 0 1 3 2 2 13
NW 1 1 2 1 3 1 3 12
Calm 2 0 2 3 3 7 3 20
.
Mean mph 6.0 6.1 5.2 4.3 3.4 2.9 2.0 4.3
Highest daily mean mph 16.3 13.2 13.3 12.1 10.6 8 5.4 16.3
Date 11 8 7 5 22 22 3 .
Mean gust 27.6 33.9 24.1 19.4 17.6 17.4 15.5 22.2
Highest gust 59 85 51 41 42 37 37 85
Date 13 8 7 5 22 22 27 .
.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year

Acknowledgements

The Met Office at RAF Valley kindly supplied observational data from 1942 to 2011. Current data (provisional) are gathered from SYNOP reports and METAR, any missing observations are initially derived from nearby stations to complete the record, up to date figures are later gathered from the Met Office website. I am grateful Ivor McLean former Met Officer at RAF Valley for early Holyhead sunshine and various other observations; David Lee for use of his observations from Gorddinog; and Gordon Perkins (BlueTractorSoftware) for observations at Gorwel Heights and additional observations.



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Page first dated 3 February 2020

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