Usually the weather in Indianapolis through September is 17 with a normal high in the month being 25 with low average temperatures being 13 degrees celsius. We have put some more detail below here:
| Month | Degrees Celsius |
|---|---|
| Temperature | 17 |
| High Temperature | 25 |
| Low Temperature | 13 |
| Sunshine Per Day | 9 |
Useful Links: Indianapolis Weather: Average Weather & Yearly Climate