The weather is set to turn unseasonably mild during the last days of 2021. There is a possibility that the current New Year's Eve temperature record, 14.8C (58.6F) set in 2011, could be beaten.
Temperatures through the rest of December and into early January will often be in double figures in much of the UK. At this time of the year the average maximum is close to 7.5C (45.5F) in the south and lower in the north.
The abnormally mild conditions will be brought about by a combination of high pressure centred to the south and low pressure to the northwest. That leads to very mild air subtropical air being pulled up from the southwest
Daffodils in bloom
The chart below shows forecast temperatures at about 1500m Above Sea Level (ASL) at 18:00 GMT, New Year's Eve. The yellows and oranges over much of the UK show an anomalously warm air mass for the time of year.
Values should be around -2C, but instead they are close to 8C. Therefore, they are a massive 10C above the norm.
Temperatures down at the ground level do not always correlate with those at 1500m ASL. For example, it can be cold at the surface even if the air mass aloft is a mild one. This is called a temperature inversion and it can happen when the days are short and conditions are very calm.
However, this week it will often be breezy or windy so the warmer air aloft will be mixing and preventing things from cooling at the surface. Hence, the conditions look ideal for some very high temperatures during both the days and nights.
The temperature chart below shows forecast maximums at 15:00 GMT, New Year's Eve. It is based on raw data from the GFS computer model which has a tendency to undershoot a little. Therefore, the maximums of 14C being forecast could easily turn out to be 15C.
It is far from certain, but a new date maximum temperature record for December 31st is definitely a possibility this year.
On some nights temperatures could remain in double figures across much of the UK and overnight records may also be challenged.
At the present time it looks as though temperatures will dip a little through the first week of January 2022, but they are expected to remain above the average.
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