December in Kotka averages a daily high of 0.8°C with nights around -3.1°C. Expect roughly 15.7 wet days totalling 52mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Kotka is June–August.
Based on KOTKA RANKKI, FI (10.2km), 1995–2024. 30 years of December data.