WEATHER · CLIMATE NORMALS · 1991–2020
Des Moines Climate — Averages by Month
What the weather in Des Moines, USaverages across a standard 30-year period. Each month's figure is the 1991–2020 mean temperature and total rainfall from the ERA5 reanalysis — the long-run normal a place settles around, not a forecast for any particular day.
Month-by-month normals
| Month | Avg temperature | Avg rainfall |
|---|---|---|
| January | -5.4 °C · coldest | 34.0 mm |
| February | -3.1 °C | 42.7 mm |
| March | 3.9 °C | 69.3 mm |
| April | 10.7 °C | 110.1 mm |
| May | 16.9 °C | 139.7 mm · wettest |
| June | 22.3 °C | 127.5 mm |
| July | 24.3 °C · warmest | 95.8 mm |
| August | 23.0 °C | 96.3 mm |
| September | 18.7 °C | 92.5 mm |
| October | 11.8 °C | 72.8 mm |
| November | 4.1 °C | 55.2 mm |
| December | -2.4 °C | 44.8 mm |
How to read these numbers
These are reanalysis normals, not readings from a single weather station. They come from the ERA5 0.25° (~25 km) global reanalysis grid, sampled at the grid cell nearest Des Moines — centred at 41.50°N, 93.50°W. A reanalysis blends observations with a physics model onto an even grid, so a coastal or mountain city's cell can read a little cooler, warmer, wetter or drier than the city centre itself. The month-to-month shape — when it's hot, when it rains — is what these normals capture best.
“Normal” means the 1991–2020 average, the current World Meteorological Organization standard period. A normal is what a place tends toward over decades — any single day, month or year can and will depart from it.