January in Hamm averages a daily high of 5.7°C with nights around 0.5°C. Expect roughly 17 wet days totalling 59.7mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Hamm is May–September.
Based on WERL, GM (12.3km), 1995–2024. 21 years of January data.