Last updated: June 24, 2025
In September, the average temperature in Indianapolis, United States hovers around 21°C (70°F), making it a comfortable destination. However, be prepared for a temperature range that can drop to a chilly 6°C (43°F) and soar up to a sizzling 33°C (92°F). Expect about 80 mm (3.2 in) of precipitation spread over 7 days, contributing to an average humidity of 69%. Whether you’re looking for milder weather or a warm escape, Indianapolis has something to offer!
In September in Indianapolis, the average temperature is 21°C (70°F), with maximums reaching up to 33°C (92°F) and minimums dropping as low as 6°C (43°F). This weather makes Indianapolis an ideal destination for travelers seeking pleasant temperatures and a variety of outdoor activities.
In Indianapolis in September, the total precipitation amount is 80 mm (3.2 in) over the course of 7 days.
In Indianapolis in September humidity is 69%. With an average temperature of 21°C (70°F), this humidity feels like a warm embrace, making outdoor activities enjoyable but requiring occasional breaks for hydration and shade during your travels.
In Indianapolis in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Indianapolis.
UV Risk Categories
Weather in Indianapolis varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Indianapolis, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -1°C (30°F) | 82 mm (3.2 inches) | 87% | moderate |
| February Weather | 1°C (34°F) | 93 mm (3.7 inches) | 85% | moderate |
| March Weather | 6°C (43°F) | 127 mm (5.0 inches) | 86% | high |
| April Weather | 11°C (52°F) | 94 mm (3.7 inches) | 84% | very high |
| May Weather | 18°C (65°F) | 132 mm (5.2 inches) | 79% | very high |
| June Weather | 23°C (74°F) | 107 mm (4.2 inches) | 82% | extreme |
| July Weather | 25°C (77°F) | 108 mm (4.2 inches) | 79% | very high |
| August Weather | 23°C (74°F) | 101 mm (4.0 inches) | 70% | very high |
| September Weather | 21°C (70°F) | 80 mm (3.2 inches) | 69% | very high |
| October Weather | 14°C (58°F) | 103 mm (4.0 inches) | 76% | high |
| November Weather | 5°C (42°F) | 93 mm (3.7 inches) | 88% | moderate |
| December Weather | 2°C (36°F) | 80 mm (3.2 inches) | 87% | moderate |