May in Waukegan averages a daily high of 19.2°C with nights around 8°C. Expect roughly 13 wet days totalling 106.8mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Waukegan is May–September.
Based on CHICAGO WAUKEGAN REGIONAL AIRPORT, IL US (7.1km), 1995–2024. 25 years of May data.