May in Madison averages a daily high of 20.8°C with nights around 8.1°C. Expect roughly 13 wet days totalling 117.5mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Madison is June–September.
Based on UW ARBORETUM MADISON, WI US (4.2km), 1995–2024. 29 years of May data.