May in Basel averages a daily high of 20.1°C with nights around 9.6°C. Expect roughly 14.4 wet days totalling 97.6mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Basel is June–September.
Based on BASEL BINNINGEN, SZ (2.9km), 1995–2024. 30 years of May data.