September in Ann Arbor averages a daily high of 24.4°C with nights around 10.6°C. Expect roughly 10.3 wet days totalling 74.2mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Ann Arbor is May–June.
Based on ANN ARBOR SE, MI US (5.6km), 1995–2024. 22 years of September data.