May in Vannes averages a daily high of 17°C with nights around 11.3°C. Expect roughly 10.5 wet days totalling 40.4mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Vannes is June–September.
Based on BELLE ILE LE TALUT, FR (52.9km), 1995–2024. 30 years of May data.