December in Bonn averages a daily high of 6.5°C with nights around 1.6°C. Expect roughly 15.9 wet days totalling 57.4mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Bonn is May–September.
Based on BONN ROLEBER, GM (6.9km), 1995–2024. 24 years of December data.