The official National Weather Service forecast for West Allis — 43.0167°N, 88.007°W, 2.1 miles from I-41. Forecasts here are written by NWS MKX, this county’s forecast office.
| Milwaukee County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 30 | 34 | 44 | 55 | 66 | 77 | 82 | 80 | 74 | 61 | 47 | 35 | 57 |
| Avg low °F | 15 | 18 | 27 | 36 | 46 | 56 | 62 | 61 | 54 | 42 | 31 | 21 | 39 |
| Precip in | 1.6 | 1.6 | 2.2 | 3.6 | 4.0 | 4.4 | 3.4 | 3.8 | 3.3 | 2.8 | 1.9 | 2.0 | 34.6 |
1996–2025 normals for Milwaukee County — the climate division West Allis sits in. All-time county record high 101.6°F (2012-07-06); record low -28.1°F (1982-01-11). Source: NOAA / National Weather Service.