December in Oslo averages a daily high of 0.7°C with nights around -3.9°C. Expect roughly 13.2 wet days totalling 53.2mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Oslo is June–September.
Based on OSLO BLINDERN, NO (3.6km), 1995–2024. 30 years of December data.