The UK could be set for the warmest December in almost 70 years as temperatures of 16C, around 10C above the average for this time of year, left Britons sweltering.
The weather has been so mild that daffodils have been begun flowering as far north as Chester and Northern Ireland.
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.