September in Oak Lawn averages a daily high of 24.9°C with nights around 15.2°C. Expect roughly 7.9 wet days totalling 78.5mm. 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 September data.