September in Evanston averages a daily high of 24.3°C with nights around 13.5°C. Expect roughly 9.2 wet days totalling 72.5mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Evanston is May–September.
Based on CHICAGO PALWAUKEE AIRPORT, IL US (19.8km), 1995–2024. 28 years of September data.