May in Winterthur averages a daily high of 18.8°C with nights around 9.2°C. Expect roughly 15 wet days totalling 127.8mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Winterthur is May–September.
Based on ZUERICH FLUNTERN, SZ (18.1km), 1995–2024. 30 years of May data.