August in Mount Prospect averages a daily high of 27.8°C with nights around 17.7°C. Expect roughly 8.9 wet days totalling 82.4mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Mount Prospect is May–September.
Based on CHICAGO PALWAUKEE AIRPORT, IL US (6.6km), 1995–2024. 29 years of August data.