December in Siegen averages a daily high of 4.2°C with nights around -1°C. Expect roughly 18 wet days totalling 79.1mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Siegen is May–September.
Based on DILLENBURG, GM (23.1km), 1995–2024. 28 years of December data.