The UK could be set for the warmest December in almost 70 years with temperatures of 16C, around 10C above the average for this time of year.
In Norfolk forecasters are predicting that on Saturday the county could break the record for the highest temperature ever recorded on December 19.
Adam Dury, a forecaster for UEA-based Weatherquest, said the highest national record for that date is 15.5C at Hemsby in 1993, and current predictions for the same date this year are for 16C in areas of west Norfolk and north of Norwich.
Mr Dury added: 'We could be in for a very warm December at the moment. We have had a very warm period over the last few days and the first half of December, and that is looking to continue for the next week, maybe through to Christmas time. We are expecting well over average temperatures.
'We should be seeing highs of about 7C but today we have got a high of 14C - double what it should be at this time of year.'
He said for the rest of this week we could see highs of 14 or 15C in Norfolk, dropping to highs of 9 or 10C at the beginning of next week.
'It could be quite a mild Christmas day - potentially 11 or 12C,' he said, adding that the national record for Christmas Day is 15.6C in Leith, in Scotland, in 1896.
Temperatures in the London area are expected to reach 16C today - above the average for May in central England of 11.2C and far higher than the December average of 6C to 8C for the UK.
A band of tropical air coming off the Atlantic from the South West is behind the unseasonable weather, and temperatures are edging towards the all-time December high of 18.3C, set on December 2 in 1948 in Highland, Scotland.
Helen Rossington, a forecaster for MeteoGroup, said: 'Yesterday we got up to 14C or 15C across the South West, but today just about everywhere is in double figures.
'In south east England, East Anglia and the London area highs are going to be around 16C. The average is around 9C at this time of year for that part of England.'
The hottest December 16 in the UK was recorded in 1972 at Aber in Gwynedd, north west Wales, when it reached 17C, and Ms Rossington suggested records for December 17 and 18, at 17.8C and 18C respectively, could be under threat.
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