January in Siegen averages a daily high of 3.6°C with nights around -2.1°C. Expect roughly 16.9 wet days totalling 77.6mm. 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. 29 years of January data.