December in London averages a daily high of 1.7°C with nights around -4.6°C. Expect roughly 16.3 wet days totalling 81.4mm. A hard month to visit for comfort alone.
Across the year, the best time to visit London is May–September.
Based on LONDON CS, ON CA (8.7km), 1995–2024. 21 years of December data.