It’s only December 10th, but London has covered by a layer of snow. Regions in northern London have got 5-10cm of snow today. On the temperature map at 11:00 today (10/12/2017) it can be seen that London is on the boundary between very warm and cold air masses:
Here is a timelapse showing the evolution of this snow episode:
This a video (unfortunately captured by a mobile) in South Kensington: