Climate averages 1991–2020
Des Moines weather
in August.
A warm, wet month: the 2nd warmest and the 9th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
August is a warm month in Des Moines: daytime highs average 27.8°C and nights cool to about 18.6°C. By daytime temperature it is the 2nd warmest of the 12 months.
Expect about 94 mm of rain on roughly 10 days, which makes August a wet month (the 9th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 13 h 51 min on an average August day.
The nearest other city in this atlas is Cedar Rapids (169 km away). In August its highs average 26.9°C, 0.9°C cooler than Des Moines, with 94 mm of rain.
Among the 498 cities listed in the United States, Des Moines ranks joint 337th of 498 for the warmest August highs and joint 349th of 498 for the driest August (rainfall, lowest first). The mean August high of those 498 cities is 29.9°C; Des Moines is 2.1°C cooler than that mean.
From August to September, average highs fall by 3.9°C to 23.9°C, and monthly rainfall falls from 94 mm to 90 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
Des Moines climate table
| Month | Average highHigh / low | Average low | Precipitation mm/month | Wet days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | -1.3°C-10.1°C | -10.1°C | 31 | 6.3 | 9.510 h |
| February | 1.4°C-8.1°C | -8.1°C | 40 | 6.5 | 10.611 h |
| March | 8.9°C-1.6°C | -1.6°C | 67 | 8.8 | 11.912 h |
| April | 15.6°C5.1°C | 5.1°C | 107 | 11.2 | 13.313 h |
| May | 21.3°C11.7°C | 11.7°C | 135 | 13.6 | 14.515 h |
| June | 26.5°C17.2°C | 17.2°C | 126 | 11.5 | 15.115 h |
| July | 28.7°C19.7°C | 19.7°C | 91 | 9.4 | 14.915 h |
| August, selected | 27.8°C18.6°C | 18.6°C | 94 | 9.5 | 13.814 h |
| September | 23.9°C14.3°C | 14.3°C | 90 | 8.0 | 12.513 h |
| October | 16.6°C7.5°C | 7.5°C | 71 | 7.8 | 11.111 h |
| November | 8.6°C0.1°C | 0.1°C | 52 | 6.8 | 9.910 h |
| December | 1.5°C-6.5°C | -6.5°C | 41 | 5.9 | 9.29 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
- Cedar Rapids in AugustUnited States · 169 kmHigh 26.9°C · Low 17.8°C · 94 mm rain
- Iowa City in AugustUnited States · 173 kmHigh 27.4°C · Low 18.4°C · 96 mm rain
- Omaha in AugustUnited States · 198 kmHigh 28.6°C · Low 19.3°C · 90 mm rain
- Saint Joseph in AugustUnited States · 229 kmHigh 29.4°C · Low 20.4°C · 91 mm rain
- Sioux City in AugustUnited States · 251 kmHigh 27.5°C · Low 18.1°C · 98 mm rain
- Davenport in AugustUnited States · 252 kmHigh 27.6°C · Low 19.0°C · 90 mm rain
- Lincoln in AugustUnited States · 271 kmHigh 29.5°C · Low 19.7°C · 80 mm rain
- Rochester (Minnesota), United States in AugustUnited States · 285 kmHigh 25.4°C · Low 17.0°C · 96 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 Des Moines) is explained once on the Des Moines year overview and on the Sources, method and limits page.