December in Koblenz averages a daily high of 5.2°C with nights around 0.2°C. Expect roughly 17.9 wet days totalling 86.9mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Koblenz is June–September.
Based on MONTABAUR, GM (18.7km), 1995–2024. 17 years of December data.