May in Skien averages a daily high of 16.9°C with nights around 5.6°C. Expect roughly 14.1 wet days totalling 67.1mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Skien is June–September.
Based on GVARV NES, NO (30.1km), 1995–2024. 28 years of May data.