WEATHER · CLIMATE NORMALS · 1991–2020
Milwaukee Climate — Averages by Month
What the weather in Milwaukee, 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 | -5.0 °C · coldest | 56.9 mm |
| February | -3.8 °C | 51.9 mm |
| March | 1.0 °C | 64.4 mm |
| April | 6.6 °C | 107.5 mm · wettest |
| May | 12.9 °C | 96.7 mm |
| June | 19.3 °C | 91.6 mm |
| July | 22.6 °C · warmest | 85.1 mm |
| August | 21.9 °C | 95.3 mm |
| September | 17.9 °C | 79.2 mm |
| October | 11.2 °C | 81.9 mm |
| November | 4.3 °C | 65.3 mm |
| December | -1.6 °C | 60.8 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 Milwaukee — centred at 43.00°N, 88.00°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.