December in Aachen averages a daily high of 5.4°C with nights around 0.9°C. Expect roughly 17.1 wet days totalling 77.5mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Aachen is June–September.
Based on NIDEGGEN SCHMIDT, GM (26.5km), 1995–2024. 30 years of December data.