December in Kotlas averages a daily high of -6.9°C with nights around -12.9°C. Expect roughly 19.8 wet days totalling 41.4mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Kotlas is June–August.
Based on KOTLAS, RS (4.3km), 1995–2024. 24 years of December data.