Llansadwrn (Anglesey) Weather:
Monthly and Annual
Summary for 2021

• Llansadwrn data table
• Gorwel Heights data table

• January
• February
• Winter
• March
• April
• May
  • Spring
• June
• July
• August
  • Summer
• September
  
  
• Acknowledgements

• Llansadwrn data table
• Gorwel Heights data table

   

  Note: Values in (.) refer to the 10-y 2011-2020 average; [.] refer to the 30-y 1991-2020 climatological average while {.} refer to the station's different LTA (long-term averages). All data are subject to verification and amendment. Javascript must be enabled to see the pop-up graphics.

  

January 2021

February 2021

March 2021

Temperatures and rainfall above average, a little duller than average

Wet and wintry at times, above average temperatures at the end of the month

Another wet month with 124.7 mm bringing the total so far this year to 451.9 mm, but 64.7 mm below last year's total. Wettest in March since 2019 and (151%) & [159%] of averages. The wettest day was on the 14th with 30.0 mm while 23.8 mm fell the next day resulting in standing water on garden and fields. Despite this there were 8 days (+0.6) with no precipitation and 13 dry days (+0.1). Rain days were 18 (-0.1); wet days 11 (-3.5); and 6 days (-2.4) had 5 mm, or more. It was drier in Llanfairfechan at Gorwel heights with 90.0 mm (103%) & [109%] of averages. The wettest day was on the 9th having 13.4 mm with 12.6 mm falling on the next day. The 27th had 12.0 mm and the 28th 11.2 mm. There were 15 dry days; 16 rain days; 13 wet days; and 8 had 5 mm, or more. Rainfall duration (wet hours) was 92h at Gorwel Heights and 99h in Llansadwrn.

It was wintry at times with sleet falling on the 11th and 26th. Hail fell on 3 days (-2.3) of average. A windy month with gales in the area on 5 days.

Temperatures were a little above normal with the mean 7.4C (+0.5) & [+0.4] of averages, highest since 2019 ranking 15th since 1979. The mean maximum was 10.3C with the highest maxima 18.6C on the 30th and 16.8C on the 31st the only two >15C. There were 15 days <10C the lowest maximum 5.6C on the 4th. The mean minimum was 4.4C (+0.8) & [+0.7] of averages. There were 2 air frosts this month the lowest -1.0C on the 6th the other -0.6C the previous day. There were 7 ground frosts, significantly (-8.0) of average, the lowest -6.4C on the 6th was (-1.7). A little warmer in Llanfairfechan at Gorwel Heights with the mean 7.9C [(+0.4)] highest since 2014. The highest maxima were 17.7C on the 30th highest since 2014 and 16.1C on the 31st. The mean minimum was 5.3C equal highest (2019) since 2017. There were no air frosts the lowest 0.8C on the 7th.

Sunshine at RAF Valley totalled 114.4h (88%) & [95%] of averages. The sunniest day was on the 1st of the month with 10.3h and there were 7 sunless days.

April 2021

Sunniest on record. Very dry, but temperatures lower than averages

Wintry at the beginning, very dry in the latter half

A very dry month with 16.7 mm of rainfall (31%) & [25%] of averages, the 6th lowest on record in Llansadwrn since records began in 1928. The lowest 6.7 mm in 1980 and 11.7 in 1984 mm are held by this station; 11.9 mm was recorded at Treffos in 1938, 13.2 mm in 1957 and 15.0 mm in 1974. There was no precipitation on 16 days (+4.4) and there were 19 dry days (+4.8). Rain days were 11 (-4.8); wet days 7 (-4.3). The wettest day with 3.6 mm fell on the 30th. At Gorwel Heights 16.6 mm fell in the month (22%) & [26%] of averages, the driest on record since 2011. There were 19 dry days; 11 rain days; 8 wet days; and none exceeded 5 mm. The wettest day on the 11th had 4.8 mm. Rainfall duration was only 25 h and at Llansadwrn 34 h.

The month had lower than average temperatures with frequent cool air from Arctic regions. Sleet or snow fell on 5 days (+4.3), the most since 1998, and small hail on 5 days (+2.2). I have not recorded any lying snow in April. The mean temperature 7.7C (-1.6) & [-1.4] of averages was lowest since 2013 ranking 8th in station records since 1979. The mean minimum 3.4C (-2.2) & [-2.0] of averages ranked 3rd lowest in records. The lowest minimum was -0.1C on the 11th, equal lowest with 2015 since 2013 that had -1.1C. There were 16 ground frosts (+9.0) the hardest -4.3C on the 11th, a record number at this station in April, previous highest 14 in 2013. The warmest day was on the 23rd having 19.8C in the afternoon with a low RH of 24% at 1632 GMT.

At Gorwel Heights the mean temperature was 7.8C (-2.1) & [-1.8] of averages, second lowest on record at this station (2012 had 7.7C). The mean maximum was 11.0C with the highest maximum 18.6C on the 23rd. The mean minimum was 4.6C, lowest 0.7C on the 11th so no air frost here.

It was a record sunny April at RAF Valley by a mile. The provisional 251 h of sunshine (one missing record on 28th estimated as 3.1h) most on the Anglesey record since 1931. The previous sunniest April was in 2015 having 232.7 h. The sunniest day was on the 22nd with 13.1h and there were no sunless days.

May 2021

Wet with temperatures below averages

Wintry at the beginning with a hint of summer at the end

Another wet month bringing the total rainfall accumulated in the year so far 608.9 mm, half the annual averages, to the most in Llansadwrn since records began in 1928 exceeding last year's record amount. Rainfall in May was 140.3 mm (208%) & [207%] of averages, ranking 3rd wettest on record only exceeded by 2015 141.3 mm and 2003 148.3 mm. May 2020 was the driest on record with only 11.9 mm.

The six wettest Mays in Treffos and Gadlys in Llansadwrn, with only a few millimetres between them, are shown in the graphic. Four of these large falls occurred in the last 40 years and two in the previous 60 years, more frequent falls are an indication of the climate changing

The wettest day was on the 20th having 35.2 mm, six days (+1.4) exceeded 5 mm and 19 were wet days (+8.8) with 1 mm, or more. There were however five days (-7.2) with no precipitation; 7 (-9.0) were dry <0.2 mm; and there were 24 (+9) rain days, those defined as having 0.2 mm, or more. Rainfall duration was 129 wet hours.

It was wet too in Llanfairfechan, at Gorwel Heights rainfall was 154.8 mm (2025) & [201%] of averages. The wettest day was on the 20th when 40.2 mm fell. There were 8 dry days; 23 rain days; 17 wet days; and 7 days had 5 mm, or more. Rainfall duration was 134 wet hours.

May followed on from April with lower than average temperatures making it a colder spring than in recent years. The mean temperature 10.6C [(-1.2)] was lowest since 2015 ranked 6 in station records since 1979. The mean maximum 14.4C (-1.1) & [-1.2] again lowest since 2015 ranked 7. The highest maximum had to wait until the 30th for 21.9C (-0.3) while the lowest was 10.9C (+0.3) on the 3rd. The mean minimum 6.7C [(-1.2)] ranked 6, the lowest 0.7C (-2.7) was on the 6th. There were 5 ground frosts (+3.6) with the lowest -2.7C (-1.7) on the 7th.

The mean temperature at Gorwel Heights 10.8C (-0.9) & [-1.7] of averages with 2013 and 2015 lowest in station records since 2011. The mean maximum 14.1C was lowest since 2015 rank 2 with the highest maximum 23.1C on the 30th. The mean minimum 7.5C was lowest in station records in May, the lowest minimum 2.2C was on the 6th again lowest in station records since 2011.

Spring 2021

With 281.7 mm rainfall it was the seventh wettest winter on record in Llansadwrn, last year with 122.7 mm was the fourth driest on record. The wettest spring was in 1947 having 352.0 mm the driest 1990 with 80.2 mm. Temperatures were below the station averages with the mean lowest since 2015.

June 2021

Drier and warmer than average and fairly sunny

Some nice summer days with awful ones in between

Rainfall was less than normal the 44.9 mm (54%) & [61%] of averages least since 2018 and ranked 25th lowest in Llansadwrn records since 1918. Despite the lower than average figures the total for the year so far 653.8 mm is the largest recorded in Llansadwrn to this date. The most rain 17.5 mm fell on the 25th, a really awful day that was also the dullest, with rainfall duration 11 h. There were, however, 16 days (+5.2) with no precipitation and 21 (+6.5) were recorded as dry (<0.2 mm). Rain days were 9 (-6.5); wet days 6 (-5.9); and 4 (-1.2) had 5 mm, or more. Rainfall duration (wet hours) was 57h.

Rainfall at Gorwel Heights was 44.2 mm (56%) & [62%] of averages. Here the wettest day was also on the 25th with 22.4 mm. Dry days were 24; rain days 6; wet days 6; and 3 had 5 mm, or more. Rainfall duration (wet hours) was 51h.

The mean temperature in Llansadwrn was 14.7C (+0.5) & [+0.7] equal highest since 2018 ranking 13th in station records since 1979. The mean maximum was 18.5C ranking 11th, highest since 2019, the highest 24.2C was on the 1st and the lowest 13.2C on the truly awful day of the 25th. The mean minimum was 11.0C lowest since 2015 ranking 9th highest while the highest 13.7C was on the 2nd and the lowest 7.9C on the 23rd, this lowest since 2015. The lowest grass minimum 4.0C (+0.9) was on the 5th.

A Gorwel Heights the mean temperature was 15.9C (+1.1) & [+1.0] of averages with the highest 20.1C was on the 2nd and lowest 11.7C on the awful 25th. The mean maximum was 19.6C with the highest 25.3C on the 13th. Twelve days had >20C with 24.3C on the 1st and 24.4C on the 2nd. The mean minimum was 12.2C with the highest 15.8C on the 2nd and the lowest 9.5C on the 4th.

Sunshine at RAF Valley was 201.3h most since 2019 and ranking 29th on the Anglesey record since 1931. The sunniest day was on the 4th with 15.7h and there were 6 sunless days.

July 2021

Warmer, drier and sunnier than average

The first half was drier than usual, but dull with average temperatures. The second half continued dry and with plenty of sunshine turned hot

It was the driest July since 2018 and ranked 38th in Llansadwrn since 1928. The 66.2 mm was (76%) & [85%] of averages. There were 15 days (+4.9) with no precipitation and 18 (+4.9) dry days. There were 13 (-4.9) rain days; 10 (-3.4) wet days; and 6 (-0.3) had 5 mm, or more. For the first month in 19 rainfall accumulated since the beginning of last year fell below the previous record total. The total accumulated so far this year is 720.0 mm. The wettest day was on the 27th having 18.9 mm and rainfall duration (wet hours) was 66h. It was wetter in Llanfairfechan, at Gorwel Heights the 78.0 mm (87%) & [98%] of averages, lowest since 2018. The wettest day was on the 27th with 15.6 mm. Rainfall duration (wet hours) was 69h.

In Llansadwrn there was a record 7 consecutive days (17-23) with a maximum temperature that reached 25C, or more. The highest temperature was 28.1C on the 22nd. The previous record was in 1989 that had 6 days (19-24), highest 28.0C. The mean for the month was 17.2C (+1.5) & [+1.4] of averages, highest since 2018 and ranking 7 in station records since 1979. The mean maximum 21.1C (+1.9) & [+1.8] of averages, again highest since 2018 and ranking 9th in station records. The mean minimum was 13.4C [(+1.1)] of averages and was equal highest since 2006 ranking 5th. The highest minimum 18.6C (+2.5) not quite a record was on the 23rd, 18.9C was recorded in 2003. The lowest minimum 11.2C (+2.5) was on the 6th and the lowest grass minimum 7.2C (+2.1) on the 16th.

At Gorwel Heights the mean temperature was 17.3C (+0.8) & [0.6] of averages, highest since 2014. The mean maximum was 20.5C, highest since 2018, with the highest 27.4C on the 23rd. There were only 3 hot days (>=25C) on the 20th, 22nd and 23rd. The mean minimum was 14.1C, highest since 2017. The highest 18.1C was on the 23rd, highest since 2019. The lowest minimum 11.4C on the 6th was highest since 2018.

August 2021

Dry with temperatures close to averages

Most rain at the beginning with a very dull spell in the middle ending warm and sunny

A drier month than average the 69.0 mm (66%) & [77%] of averages, least since 2018 and much less than last August's 168.5 mm. The wettest day was on the 7th having 21.6 mm the third day of a wet spell 5-7th that had 40.4 mm 59% of the month's total. The 20th another wet day had 12.0 mm. Days with no precipitation total 8 (+0.8) and dry days 18 (+6.4). Rain days were 13 (-0.4); wet days 9 (-4.9); and days with 5 mm, or more, were 4 (-1.1). Rainfall at Gorwel Heights in Llanfairfechan was 62.8 mm (62%) & 71%] of averages, least on the 10-y station record. The wettest day was 7th with 23.4 mm. There were 21 dry days; 10 rain days; 10 wet days; and 5 had 5 mm, or more. Rainfall duration (wet hours) was 67h and in Llansadwrn 85h.

Temperatures were close to averages, there were no hot >25C days with 8 warm days reaching 20C, or more, with 5 of them in a spell 22-26th. The mean maximum was 18.6C (+0.3) & [-0.3] of averages with the highest a modest 21.9C on the 25th (-1.5). The mean minimum was 12.5C (+0.1) & [+0.2) with the highest 14.7C on the 6th and lowest 10.3C on the 2nd (+2.2). The mean temperature 15.6C was lowest since 2017. Gorwel Heights had 8 warm days (>20C) with a mean maximum of 19.0C the highest 22.9C on the 11th and lowest 15.8C on the 17th. The mean minimum was 13.3C with the highest 14.9C on the 21st and the lowest 11.1C on the 2nd. The mean temperature 16.2C lowest since 2018 was on the 10-y average and [-0.6] on the 30-y average.

Summer 2021

Driest since 2018 and ranking 27th driest in Llansadwrn records back to 1928. Temperatures were above the averages with the mean 15.9C highest since 2018 ranking 19th in station records since 1979.

September 2021

Record high temperatures, duller with above average rainfall

Dry with two hot days and a thunder storm at the beginning turning wetter with cooler autumnal thundery weather at the end

Two hot days with maxima of 25.2C on the 7th and 28.2C on the 8th highest of the month and year, just pipping the 28.1C on 22nd July with 28.3C at Gorwel Heights on the 8th the highest in September since before 2011. The 28.2C in Llansadwrn was the highest in September on record beating the 28.0C on 4th 2005. The mean maximum in Llansadwrn was 19.1C highest since 2014 and third highest since before 1979. The mean minimum temperature 12.7C and the highest minimum 18.0C on the 8th were also September record highs at this station. At Gorwel Heights the mean minimum 13.5C and highest minimum 18.2C on the 8th were highest on record since before 2011.

September one of the wetter months of the year exceeding 100 mm the 44th in records back to 1928. It began on the dry side, but with a fall of 15.8 mm on the 5th and a wet end with 31.2 mm on the 26th, largest of the month, the 113.7 mm accumulated (109%)& [112%] of averages, ranked 38th and was largest since 2019. Rainfall at Gorwel Heights 124.0 mm (126%) &[129%] of averages was also wettest since 2019 with the largest fall 38.0 mm on the 26th. Rainfall duration (wet hours) was 76h at Gorwel and 97h in Llansadwrn with the rain per hour 1.6 mm and 1.2 mm respectively. Dry days were 12 and 13; rain days 18 and 17; wet days 10 each; and days with 5 mm, or more, 10 each station.

Sunshine at RAF Valley was 117.5h lowest since 2017. The sunniest day was on the 7th with 12.0h and there were 4 sunless days.