May in Kotka averages a daily high of 12.6°C with nights around 5.9°C. Expect roughly 8 wet days totalling 34.7mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Kotka is June–August.
Based on KOTKA RANKKI, FI (10.2km), 1995–2024. 28 years of May data.