Indianapolis weather by month
Indianapolis runs from about -2°C in January to 24°C in July, with April the wettest month at 161 mm.
warmest month
July
24°C
coolest month
January
-2°C
wettest month
April
161 mm
worst air month
February
14 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | -2°C | 125 mm | 125 h | 9 |
| February | 4°C | 36 mm | 256 h | 14 |
| March | 8°C | 136 mm | 247 h | 8 |
| April | 13°C | 161 mm | 276 h | 7 |
| May | 19°C | 108 mm | 344 h | 6 |
| June | 23°C | 81 mm | 340 h | 8 |
| July | 24°C | 95 mm | 382 h | 10 |
| August | 23°C | 63 mm | 374 h | 10 |
| September | 21°C | 105 mm | 296 h | 9 |
| October | 15°C | 14 mm | 306 h | 6 |
| November | 9°C | 115 mm | 162 h | 6 |
| December | 2°C | 118 mm | 155 h | 9 |
About 3,263 hours of sun a year. Roughly 118 rainy days a year.
These are long-run climate normals, not a forecast. A given year can sit well outside them. PM2.5 is a global model: near the coast it counts sea salt as fine particulate and reads high against ground stations, sometimes by a factor of two. Use the shape of the year, not the absolute number.
where these numbers come from
- · Temperature, rainfall and sunshine: ECMWF ERA5 reanalysis climate normals via Open-Meteo (CC BY 4.0), fetched once and stored.
- · PM2.5: Copernicus CAMS reanalysis, monthly means. Modelled, not station readings; near coasts CAMS counts sea salt as PM2.5 and reads high.
Last reviewed 2026-05-23. Full method, licences and the list of sources we rejected are on the methodology page.