Latest annual report shows the impact of global temperature rises on the climate in the UK

• 2021 was 0.1°C warmer than the 1991–2020 average, and 18th warmest in the UK series from 1884. It was warmer than all but one year in this series prior to 1990.
• Winter and spring were colder than the 1991–2020 average. However, 2021 included the UK’s ninth warmest summer and equal-third warmest autumn on record in series from 1884.
• All the top ten warmest years for the UK in the series from 1884 have occurred this century.
• The most recent decade (2012–2021) has been on average 0.2°C warmer than the 1991–2020 average and 1.0°C warmer than 1961–1990.
• The 21st century so far has been warmer than any period of equivalent length from the last three centuries as shown by the Central England temperature series.

• The numbers of air and ground frosts in 2021 were above the 1991–2020 average.
• The numbers of air frosts and ground frosts in April 2021 were the highest on record for the UK in series from 1960.
• The most recent decade (2012–2021) has had 5% fewer days of both air and ground frost compared to the 1991–2020 average, and 21%/18% fewer compared to 1961–1990.

• Heating and cooling degree days in 2021 were near the 1991–2020 average. Growing degree days were seventh highest for the UK in a series from 1960.
• The most recent decade (2012–2021) has had 2% fewer heating degree days per year on average compared to 1991–2020 and 11% fewer compared to 1961–1990.
• The most recent decade (2012–2021) has had 2% more growing degree days per year on average compared to 1991–2020 and 17% more compared to 1961–1990.

• 2021 was ranked 20th warmest year for UK near-coastal sea-surface temperature (SST) in a series from 1870.
• The most recent decade (2012–2021) has been on average 0.1°C warmer than the 1991–2020 average and 0.7°C warmer than 1961–1990.
• Nine of the ten warmest years for near-coast SST for the UK have occurred this century.

• 2021 rainfall was 95% of the 1991–2020 average and 102% of the 1961–1990 average.
• 2021 included the UK’s fifth driest April and second wettest May in monthly series from 1836.
• Five of the ten wettest years for the UK in a series from 1836 have occurred this century.
• Since 2009, the UK has had its wettest February, April, June, November and December on record in monthly series from 1836—five of 12 months—as well as its wettest winter.
• The most recent decade (2012–2021) has been on average 2% wetter than 1991–2020 and 10% wetter than 1961–1990 for the UK overall.
• For the most recent decade (2012–2021) UK summers have been on average 6% wetter than 1991–2020 and 15% wetter than 1961–1990. UK winters have been 10%/26% wetter.

• For a week in early February the UK experienced its most widespread and significant snow event since late February to early March 2018.
• In terms of overall snowiness, 2021 was a fairly average year when compared to the last 60 years, whereas in the last ten years 2012–2021, only 2013 and 2018 were snowier.
• Widespread and substantial snow events have occurred in 2021, 2018, 2013, 2010 and 2009, but their number and severity have generally declined since the 1960s.

• The UK 2021 annual sunshine total was 99% of the 1991–2020 average.
• April 2021 was the UK’s equal-sunniest April on record in a series from 1919, shared with April 2020, and also the sunniest calendar month of the year.
• The most recent decade (2012–2021) has had for the UK on average 2% more hours of bright sunshine than the 1991–2020 average and 8% more than the 1961–1990 average.
• For the most recent decade (2012–2021) UK winters have been 3% sunnier than 1991–2020 and 13% sunnier than 1961–1990. UK springs have been 6%/15% sunnier.

• With the notable exception of storm Arwen, the year was less stormy than most other years in recent decades.
• There have been fewer occurrences of max gust speeds exceeding 40/50/60 Kt for the last two decades compared to the 1980s and 1990s.
• The UK annual mean wind speed for 2021 was second lowest in a series from 1969.
• The UK annual mean wind speed from 1969 to 2021 shows a downward trend, consistent with that observed globally. However, this series must be interpreted with some caution.

• The rate of sea-level rise in the UK is increasing, with selected locations recording a range from 3.0 ± 0.9 to 5.2 ± 0.9 mm·year⁻¹ over the past 30 years when corrected for vertical land movement, compared to the 1.5 ± 0.1 mm·year⁻¹ since 1900s.
• For the 20th century the rate of sea-level rise around the UK is close to the estimate of the global sea-level rise.
• Storm surges of over 1.5 m were seen during Storm Arwen, but extreme sea levels were avoided as this occurred during low water and a neap tide.

• Easterly winds brought widespread freezing conditions and snow to the UK from February 7–13, 2021, the most severe spell of winter weather since February–March 2018.
• On July 21, 2021 31.3°C was recorded at Castlederg, County Tyrone, setting a new all-time temperature record for Northern Ireland.
• Two rain-gauges in Cumbria recorded daily totals exceeding 200 mm during some exceptionally wet weather across northern England and southern Scotland in late October. There has been a marked in increase in such observations in recent years.
• A red warning was issued for storm Arwen on November 26–27, 2021, one of the most damaging winter storms of the latest decade. Unusually, the strongest winds were from a northerly direction.

• First leaf dates in 2021 were earlier than the baseline (1999–2020) for species that leaf earlier in the season (e.g., Elder normally in March), but delayed by the cold April for later leafing species (e.g., Pedunculate Oak normally in April). This resulted in a mixed spring overall.
• Bare tree dates in 2021 were 2–5 days later than normal with Pedunculate Oak pushed back to early December.
• Overall, the 2021 leaf-on season was only 1–7 days longer than the 1999–2020 baseline because of the colder spring.

The full report can be read here.

Feature image from https://twitter.com/spatialanalysis