The mildest start to December has been recorded in Wales (8.7C), south west England (9.8C) and south east England (10C) since 1960. The past few weeks have also been recorded as the 4th warmest December on record for the whole of the UK, with 1979, 2000 and 2006 being only marginally milder.
The figures have been recorded for the first two weeks of December (1-14) and show that the first half of the month has been exceptionally warm across England and Wales. Maximum daily temperatures have been 3.2C above average – however, there appears to have been a stark difference between the north and the south this month.
A spokesperson for the Met Office said: "There has been a sharp north-south contrast at times with much colder air over Scotland and some frosts. Elsewhere the humid south-westerly airflow means the weather has remained similar to last month: cloudy with very few clear nights, mild nights and very little sunshine for most areas."
Last month was noted as the warmest November month on record, with temperatures reaching as high as 22.4C in Wales. Overnight temperatures remained mild as well, reaching up to 16C in Northern Ireland on 9-10 November night. November was also recorded as the fifth-wettest ever for south-west Scotland.
However, December appears to be wetter than November, with 200% of the month's normal rainfall levels having already fallen in a few places. The main source of the rainfall was during Storm Desmond earlier on in the month, which brought record-breaking rainfall levels over the Lake District.
"Indications are that the unsettled weather will continue through Christmas and into the New Year," the Met Office said. "Showers or longer spells of rain are expected across all parts, with the heaviest and most persistent rain in the north and west."
The south-east of England is expected to see drier conditions, with more mild weather. Temperatures are believed to remain above average throughout the rest of the month, slashing hopes for a White Christmas in many regions.