May in Reykjavík averages a daily high of 10.2°C with nights around 4°C. Expect roughly 17.6 wet days totalling 68mm. Demanding conditions — pack for it and plan indoor options.
Across the year, the best time to visit Reykjavík is June–August.
Based on REYKJAVIK, IC (1km), 1995–2024. 30 years of May data.