Climate averages 1991–2020
Indianapolis weather
by month.
See how the year changes. July has the highest average daily maximum; February has the lowest average monthly rainfall.
Pleasant-weather months by our simple rule: September
Long-term climate patterns, not a forecast for a particular trip.
Across the year Indianapolis averages a daytime high of 16.3°C and a nighttime low of 7.4°C, with about 1,075 mm of rain on roughly 121 days. July is the warmest month (average high 28.5°C) and January the coolest (1.9°C). May is the wettest month with 122 mm; February is the driest with 66 mm.
Months with pleasant weather by a simple rule (average high between 18°C and 29°C, average low of at least 5°C and at most 8 rain days): September. This looks at temperature and rain only, not humidity, wind, sea temperature or crowds.
The annual picture
A year in Indianapolis
Monthly precipitation
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Indianapolis climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 1.9°C-6.0°C | -6.0°C | 80 | 9.2 | 9.710 h |
| February | 4.4°C-4.5°C | -4.5°C | 66 | 8.6 | 10.711 h |
| March | 10.1°C0.4°C | 0.4°C | 97 | 11.1 | 11.912 h |
| April | 16.8°C6.5°C | 6.5°C | 120 | 12.0 | 13.213 h |
| May | 22.0°C12.4°C | 12.4°C | 122 | 13.4 | 14.314 h |
| June | 26.7°C17.5°C | 17.5°C | 107 | 11.8 | 14.915 h |
| July | 28.5°C19.5°C | 19.5°C | 90 | 11.5 | 14.715 h |
| August | 28.0°C18.9°C | 18.9°C | 72 | 8.9 | 13.714 h |
| September | 24.6°C15.2°C | 15.2°C | 72 | 7.6 | 12.512 h |
| October | 17.7°C8.9°C | 8.9°C | 83 | 8.4 | 11.211 h |
| November | 10.2°C2.5°C | 2.5°C | 87 | 8.8 | 10.010 h |
| December | 4.2°C-2.9°C | -2.9°C | 78 | 9.9 | 9.49 h |
Precipitation (rain or snow, as water) is the average of the 30 separate monthly totals. A wet day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
Nearby cities
- CarmelUnited States · 24 kmHigh 15.9°C · Low 7.0°C · 1,054 mm rain a year
- FishersUnited States · 24 kmHigh 16.0°C · Low 6.9°C · 1,054 mm rain a year
- Bloomington (Indiana), United StatesUnited States · 74 kmHigh 17.1°C · Low 8.1°C · 1,131 mm rain a year
- MuncieUnited States · 81 kmHigh 15.6°C · Low 6.5°C · 1,032 mm rain a year
- Lafayette (Indiana), United StatesUnited States · 94 kmHigh 15.9°C · Low 6.7°C · 1,002 mm rain a year
- CincinnatiUnited States · 158 kmHigh 17.1°C · Low 7.7°C · 1,087 mm rain a year
- DaytonUnited States · 168 kmHigh 16.3°C · Low 7.5°C · 1,066 mm rain a year
- LouisvilleUnited States · 172 kmHigh 18.6°C · Low 9.2°C · 1,169 mm rain a year
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsWhat do the high and low temperatures mean?
We average the daily maximum and daily minimum for each calendar month over 1991–2020. They are not record extremes, a forecast range or temperatures at a fixed time of day.
How is a rain day counted?
A local calendar day (standard time, UTC-5, no daylight saving) with at least 1 mm of total precipitation counts as one rain day. We count these for each year and month, then average across 30 years. The average does not predict which days will be wet.
Where do the numbers come from?
ERA5-Land (temperature) and ERA5 (precipitation) reanalysis from the Copernicus Climate Change Service, read from the Open-Meteo open-data archive. Temperature comes from the 0.1° model cell at 39.80°, -86.20° (5 km from the city centre), adjusted down by 0.1°C for the difference between the city's elevation (248 m) and the cell's (234 m). Rain comes from the 0.25° cell at 39.75°, -86.25°. These are model estimates, not weather-station readings; coast, hills and city streets can differ.
Does this page show sunshine, humidity or sea temperature?
No. The data used here contain air temperature and precipitation only. Daylight hours are calculated from the city's latitude (sunrise to sunset), not measured sunshine.