December in Reykjavík averages a daily high of 3.2°C with nights around -1.7°C. Expect roughly 20.7 wet days totalling 103.5mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Reykjavík is June–August.
Based on REYKJAVIK, IC (1km), 1995–2024. 30 years of December data.