Today, Sussex is enjoying temperatures as high as 17C (62.6F) and the unseasonable weather is set to continue this side of Christmas.
The average maximum temperature for the UK in December is normally 6.7C (44.06F).
Lindsay Mears from the Met Office said: “It is pretty mild for this time of year, which is quite exceptional.
“It’s due to the warm air forming in from the Atlantic and bring with it a lot of rain and cloud, which keeps the temperatures quite mild, instead of the bright clear skies which we see when temperatures go down.
“For today we will see 16C (60.8F) to 17C in parts and 8C to 9C in the north.
And the accompanying cloud and showers and persistent rain, which will carry on throughout the rest of the week.
“The temperatures for the whole country are quite amazing for this time of year.”
However, forecasters say moving into Friday the wind direction is set to change and come from the west, bringing fresher air.
It looks as though mild unseasonable weather is set to continue into the festive week.
Ms Mears said: “We are looking at a bit of an unsettled picture, so carrying on with the rain and cloudy in areas, but it’s too early yet to say what will happen yet.”
Explaining the mild spell, she said: “The weather hasn’t changed particularly, it’s just to do with where the wind coming from, and at the moment it’s coming from the Atlantic.
“Sometimes we might the continental cold air, or the Scandinavian air.
“It’s not unusual to have storms, rain, wind and cloudy weather at this time of year, but the temperatures are a lot warmer than average and are exceptionally warm for this time of year.
“But it is still very early in the winter and we are only just getting the season.”
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