May in Dayton averages a daily high of 24.1°C with nights around 12.5°C. Expect roughly 13.5 wet days totalling 113.3mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Dayton is September–October.
Based on DAYTON MCD, OH US (2.5km), 1995–2024. 25 years of May data.