August in Des Plaines averages a daily high of 28.1°C with nights around 18°C. Expect roughly 9.2 wet days totalling 103mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Des Plaines is August–September.
Based on CHICAGO OHARE INTERNATIONAL AIRPORT, IL US (9.1km), 1995–2024. 30 years of August data.