September in Indianapolis averages a daily high of 26°C with nights around 14.5°C. Expect roughly 7.4 wet days totalling 78.1mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Indianapolis is September–October.
Based on INDIANAPOLIS INTERNATIONAL AIRPORT, IN US (12.5km), 1995–2024. 30 years of September data.