UK climate

April 2021 – Coldest Average Minimum CET Since Records Began

If you live in Central England and you thought the nights were exceptionally chilly last month, for April, the second month of Spring, then you would be right. There were numerous frosts throughout the month. I woke up to a hard ground frost on the east coast on St George’s Day and the grass was still frosted in the shade even hours after sun up. The days were cold too, but the nights were something special. So special in fact that April 2021 earns first place by a considerable margin for the coldest average April min CET since records began in 1878. April 2021 min CET = 1.0C. The next coldest April is 1917 at 1.4C, nearly half a degree warmer! That is really quite remarkable. April 1986, in terms of mean diurnal CET, was colder than April 2021 (5.8C vs. 6.4C) but the nights in 1986 were a lot warmer (2.2C vs. 1.0C), even though the days were colder. This undoubtedly comes down to the fact that April 2021 was also very sunny throughout the UK, raising daytime tempertures, but allowing them to plummet in the relentless northerly airflow, which brought cold air from the Arctic over the British Isles throught the entire month.

For the UK as a whole, the Met Office says that April 2021 saw the coldest average minmum temperatures for nearly 100 years:

April 2021 had the lowest average minimum temperatures for April in the UK since 1922, as air frost and clear conditions combined for a frost-laden, chilly month, despite long hours of sunshine.

It was very sunny:

Despite the low minimum temperatures and frosts, much of the UK has been basked in sunshine through April, with all UK countries currently reporting sunshine hours for the month in their top five ever recorded since 1919. This has provisionally seen Scotland and Wales break their existing records for sunshine hours in the month, with the two countries seeing 57% and 45% more sunshine than their long term averages. For Scotland, this would represent the second year running that April’s sunshine hours have broken the existing record, with 2021’s current figure of 211.5 topping 2020’s 204.6 to top the standings.  

The final figures for 2021 don’t appear to be in yet, but April 2021 is definitely challenging 2020 as the sunniest month on record.

Currently the UK is experiencing its second sunniest April on record, with 218.8 hours. As the figures won’t include today’s sunshine totals, there is scope for this figure to rise further, potentially challenging the April record set last year with 224.5 hours. The UK saw 48% more sunshine hours than April’s average figure, and every country in the UK saw at least 40% more sunshine than the long-term average. 

The irony here is that last year’s very sunny April – when the murderous sociopath Matt Hancock banned sunbathing and was threatening to ban all outdoor exercise for everyone because of a nasty bug going round – was also very warm, unlike this year of course. That was inevitably linked to climate change. Dr. Mark McCarthy, for example, wasted no time identifying a trend of warm Aprils due to the UK’s changing climate:

Dr Mark McCarthy is the head of the Met Office’s National Climate Information Centre. He said: “Although April 2020 will be remembered for being the sunniest April on record in England and the UK, along with the sunshine, the month was largely dry with mean temperatures well above average for most parts of the UK. The UK climate is warming, and it is notable that in a Met Office series from 1884 the Aprils of 2003, 2007, 2009, 2011, 2014 and 2020 are all in the top ten warmest.”

Strangely though, he hasn’t done the same this year! Global warming in the UK works in mysterious ways. It makes April sunnier and sunnier, and warmer and warmer, until suddenly it doesn’t and instead it makes April nights the coldest ever recorded going back to 1878, with the days not much better. Of course, real meteorologists know that the clue to this apparently bizarre weather is the changing spring jet stream configuration over the British Isles (and possible decadal trends in that configuration); atmospheric dynamics rather than simple thermodynamics. However, the all-singing, all dancing climate models don’t have much to say about that.