May in Oak Lawn averages a daily high of 21.7°C with nights around 11.2°C. Expect roughly 12.6 wet days totalling 124.2mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Oak Lawn is August–September.
Based on CHICAGO MIDWAY AIRPORT 3 SW, IL US (3.3km), 1995–2024. 30 years of May data.