May in Naperville averages a daily high of 21.7°C with nights around 9.5°C. Expect roughly 13.1 wet days totalling 125mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Naperville is August–September.
Based on AURORA WATER, IL US (13.4km), 1995–2024. 29 years of May data.