The Met Office stated this afternoon that a weather station recorded 18.7C in Achfary, on the North Coast of Scotland. It will need to be quality checked, and if verified it will become the highest temperature recorded during the month of December in the UK.
You might think this part of the UK is the least likely place to see the highest temperature recorded during December. However, if winds are from a certain direction and are strong enough, having masses of highground can promote pockets of warmth at lower levels. This Meteorological phenomenon is known as the Foehn effect, and is common in the UK during the Autumn and Winter months.