May in Rockford averages a daily high of 21.9°C with nights around 9.6°C. Expect roughly 13.2 wet days totalling 108.8mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Rockford is August–September.
Based on ROCKFORD GREATER ROCKFORD AIRPORT, IL US (8.7km), 1995–2024. 30 years of May data.