Indianapolis, Indiana weather in September

Averages from 2021–2025 (150 days of record).

Average high: 79°F
Average low: 60°F
Rainy days: ~8 per month
Total precipitation: 2.8 in
Warmest recorded: 90°F
Coldest recorded: 43°F

Expect September days in Indianapolis, Indiana to top out around 79°F and cool to about 60°F overnight, with roughly 8 days of measurable rain across the month. In recent years September has ranged from 43°F to 90°F.

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Current Indianapolis, Indiana forecast → · Historical data by Open-Meteo (ERA5).