Climate averages 1991–2020
Indianapolis weather
in August.
A hot, moderately wet month: the 2nd warmest and the joint 2nd driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
August is a hot month in Indianapolis: daytime highs average 28.0°C and nights cool to about 18.9°C. By daytime temperature it is the 2nd warmest of the 12 months.
Expect about 72 mm of rain on roughly 9 days, which makes August a moderately wet month (the joint 2nd driest of the 12 months). Daylight, from sunrise to sunset, lasts about 13 h 44 min on an average August day.
The nearest other city in this atlas is Carmel (24 km away). In August its highs average 27.5°C, about as warm as Indianapolis, with 74 mm of rain.
Among the 498 cities listed in the United States, Indianapolis ranks joint 325th of 498 for the warmest August highs and joint 230th of 498 for the driest August (rainfall, lowest first). The mean August high of those 498 cities is 29.9°C; Indianapolis is 1.9°C cooler than that mean.
From August to September, average highs fall by 3.4°C to 24.6°C, and monthly rainfall stays at 72 mm.
The annual picture
August in context
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, selected | 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
August in nearby cities
- Carmel in AugustUnited States · 24 kmHigh 27.5°C · Low 18.5°C · 74 mm rain
- Fishers in AugustUnited States · 24 kmHigh 27.6°C · Low 18.4°C · 74 mm rain
- Bloomington (Indiana), United States in AugustUnited States · 74 kmHigh 28.8°C · Low 19.3°C · 79 mm rain
- Muncie in AugustUnited States · 81 kmHigh 27.1°C · Low 18.0°C · 79 mm rain
- Lafayette (Indiana), United States in AugustUnited States · 94 kmHigh 27.6°C · Low 18.4°C · 82 mm rain
- Cincinnati in AugustUnited States · 158 kmHigh 28.5°C · Low 18.9°C · 75 mm rain
- Dayton in AugustUnited States · 168 kmHigh 27.9°C · Low 18.9°C · 81 mm rain
- Louisville in AugustUnited States · 172 kmHigh 30.0°C · Low 20.2°C · 71 mm rain
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 limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Indianapolis) is explained once on the Indianapolis year overview and on the Sources, method and limits page.