May in Iserlohn averages a daily high of 17.1°C with nights around 7.3°C. Expect roughly 14.2 wet days totalling 79.5mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Iserlohn is June–September.
Based on LUDENSCHEID, GM (14.9km), 1995–2024. 30 years of May data.