December in Kouvola averages a daily high of -1.5°C with nights around -6.5°C. Expect roughly 19.1 wet days totalling 65mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Kouvola is May–August.
Based on KOUVOLA UTTI LENTOPORTINTIE, FI (13.5km), 1995–2024. 30 years of December data.