The official National Weather Service forecast for Grafton — 43.3197°N, 87.9534°W, population 44,086, 5.6 miles from I-43. Forecasts here are written by NWS MKX, this county’s forecast office.
| Ozaukee County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 29 | 32 | 43 | 54 | 65 | 76 | 81 | 79 | 73 | 60 | 46 | 34 | 56 |
| Avg low °F | 14 | 16 | 25 | 35 | 45 | 55 | 61 | 60 | 53 | 41 | 30 | 20 | 38 |
| Precip in | 1.5 | 1.4 | 2.1 | 3.4 | 3.8 | 4.3 | 3.4 | 3.9 | 2.9 | 2.7 | 1.9 | 1.9 | 33.2 |
1996–2025 normals for Ozaukee County — the climate division Grafton sits in. All-time county record high 101.3°F (2012-07-06); record low -29.1°F (1982-01-11). Source: NOAA / National Weather Service.