December in Sundsvall averages a daily high of -1.1°C with nights around -7.9°C. Expect roughly 13.8 wet days totalling 63.4mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Sundsvall is June–August.
Based on SIDSJO, SW (1.5km), 1995–2024. 11 years of December data.