May in Iowa City averages a daily high of 22.7°C with nights around 10.6°C. Expect roughly 12.8 wet days totalling 112.9mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Iowa City is August–October.
Based on IOWA CITY MUNICIPAL AIRPORT, IA US (2.7km), 1995–2024. 29 years of May data.