May in Mainz averages a daily high of 20.3°C with nights around 10.1°C. Expect roughly 11.6 wet days totalling 55.2mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Mainz is May–September.
Based on MAINZ LERCHENBERG ZDF, GM (5.1km), 1995–2024. 29 years of May data.