Climate averages 1991–2020
Des Moines weather
in September.
A warm, wet month: the 4th warmest and the 7th driest of the year. Meets the pleasant-weather rule
Long-term climate patterns, not a forecast for a particular trip.
September is a warm month in Des Moines: daytime highs average 23.9°C and nights cool to about 14.3°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 90 mm of rain on roughly 8 days, which makes September a wet month (the 7th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 31 min on an average September day.
The nearest other city in this atlas is Cedar Rapids (169 km away). In September its highs average 23.2°C, 0.7°C cooler than Des Moines, with 100 mm of rain.
Among the 498 cities listed in the United States, Des Moines ranks joint 361st of 498 for the warmest September highs and joint 340th of 498 for the driest September (rainfall, lowest first). The mean September high of those 498 cities is 26.9°C; Des Moines is 3.0°C cooler than that mean.
From September to October, average highs fall by 7.2°C to 16.6°C, and monthly rainfall falls from 90 mm to 71 mm.
The annual picture
September 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 | 27.8°C18.6°C | 18.6°C | 94 | 9.5 | 13.814 h |
| September, selected | 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
September in nearby cities
- Cedar Rapids in SeptemberUnited States · 169 kmHigh 23.2°C · Low 13.7°C · 100 mm rain
- Iowa City in SeptemberUnited States · 173 kmHigh 23.7°C · Low 14.2°C · 99 mm rain
- Omaha in SeptemberUnited States · 198 kmHigh 24.8°C · Low 14.8°C · 77 mm rain
- Saint Joseph in SeptemberUnited States · 229 kmHigh 25.2°C · Low 15.7°C · 85 mm rain
- Sioux City in SeptemberUnited States · 251 kmHigh 23.8°C · Low 13.8°C · 75 mm rain
- Davenport in SeptemberUnited States · 252 kmHigh 23.8°C · Low 14.8°C · 88 mm rain
- Lincoln in SeptemberUnited States · 271 kmHigh 25.5°C · Low 15.2°C · 71 mm rain
- Rochester (Minnesota), United States in SeptemberUnited States · 285 kmHigh 21.4°C · Low 12.9°C · 84 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.