December was a hot, dull month that ended with record high temperatures on New Years Eve, the Met Office said.
While unusually high temperatures on the last day of the year grabbed the headlines, the average minimum temperatures – how badly the mercury drops each night – for the month were also particularly high.
Abnormally mild conditions in mid-December and late December were caused by high pressure on the UK, but background warming from climate change has made it more likely that the heat will “switch” to record territory , said the Met Office.
When we see these weather patterns, they are more likely to tip into record high temperatures due to this 1.1 ° C background of global warming.
The balmy end of December saw the UK hit its highest New Years Eve temperature on record, 16.5C in Bala, North Wales, as highs exceeded 15C in the four countries of the United Kingdom.
Some weather stations have broken long-standing individual records for the month, such as Cromer in Norfolk, which had its hottest December day with records going back 103 years, reaching 15.4 ° C on December 30.
Met Office spokesman Stephen Dixon said: ‘Climate change is not responsible for the weather conditions we’ve seen – we’ve had hot December and hot New Years Eve, but it was a record.
“What this means is that when we see these weather patterns, they are more likely to tip into record high temperatures due to this 1.1 ° C background of global warming.”
He added that records for high temperatures were being challenged nine times more than low temperatures.
In December, particularly high minimum temperatures stand out, especially in southern areas, the Met Office said.
The UK had an average December low of 2.8C, 1.4C above the long-term average from 1991 to 2020, but well below the record of 5.2C for the month set in 2015.
In the south of England, average minimum temperatures were 4.3 ° C – 2 ° C above the month’s average – and there were “unusually balmy” nights with cloudy and sunny conditions. air sucked in from the Azores.
Daily minimum temperatures on New Years Eve remained largely in double digits, and resorts like Sheffield, Bradford and Buxton recorded their highest daily minimums in records dating back more than 100 years, at around 10C higher than the monthly average.
The monthly average minimum temperatures were driven by heat waves in the middle and end of the month, again due to the high pressures.
But the key factor was that the weather conditions created cloudy conditions for many that prevented severe frosts and kept nighttime temperatures high, the Met Office said.
In cloudy conditions, the UK experienced its fifth gloomiest and darkest December on record since 1956, averaging just 27.6 hours of sunshine, according to Met Office figures.
For gardeners, the dull but warm conditions meant that winter vegetables such as Brussels sprouts and leeks continued to grow and camellias and Christmas roses were not spoiled.
Guy Barter, Chief Horticultural Advisor at the Royal Horticultural Society, said: “The weeds also continued to grow, but in dull conditions they will not give seed and can be spared for now to help the wildlife.
“Lawns remain remarkably green, but growth has been limited by a lack of light, so the lawn mower can rest a bit longer. “
Rainfall has been near average for much of the UK, according to monthly data.
A White Christmas has been declared by the Met Office as elevated areas of northern UK saw a flurry of snow.
Mike Kendon, National Climate Information Center, said: “December will be remembered for the most part for the unusual heat we saw in the middle and end of the month.
“As a result, we saw relatively few days of freezing ground and freezing air and less cold weather than you would normally expect in early winter, although some places in the north experienced hard frosts. .
“There were also remarkable temperature inversion conditions for several days in Scotland, where the hottest and sunniest spot was across the mountain peaks.”