So 5 years ago it was cold in December but the next year it was......:-

December 2011. A very westerly month with frequent gales (the second most westerly December on record). Overall it was warmer than average, making it the mildest December since 2006, although it was warmest in southern England and coolest in Northern Ireland. The highest temperature of the month was 15.5C at Fyvie (Aberdeenshire) on the 26th, and the lowest -9.4C at Loch Glascarnoch (Wester Ross) early on the 18th. It didn't reach above -3.0C at Aviemore on the 16th. It was slightly wetter than average in England and Wales, with 112mm of rain (115%). Although it was sunnier than the long-term average (55 hours, 105 hours) it was the least sunny December for some years. A phenomenal gale causes widespread disruption on Thursday 8th, especialy to central and southern Scotland. Bridges shut. A gust of 165 mph is recorded on Cairngorm. It's a green and mild Christmas, with 15.1C recorded at Aberdeen, not far from the previous record of 15.6C in 1896 and 1920. Northern Ireland had its warmest Christmas Day on record: 14.3C at Murlough, County Down. It's also a very windy day, especially across the north, with gusts of 101 mph at Sella Ness in Shetland and a severe gale in Orkney and Shetland. There was another severe gale in central Scotland on the 28th.

I think some of the recorders don't keep track of their own "records"?