The official National Weather Service forecast for Beloit — 42.5084°N, 89.0318°W, population 63,073, 2.2 miles from I-39. Forecasts here are written by NWS MKX, this county’s forecast office.
| Rock County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 28 | 33 | 45 | 59 | 70 | 80 | 83 | 81 | 75 | 62 | 47 | 34 | 58 |
| Avg low °F | 13 | 16 | 26 | 36 | 47 | 58 | 62 | 60 | 52 | 41 | 30 | 19 | 38 |
| Precip in | 1.5 | 1.6 | 2.2 | 3.5 | 4.2 | 5.3 | 4.1 | 4.2 | 3.5 | 2.9 | 2.1 | 1.9 | 37.0 |
1996–2025 normals for Rock County — the climate division Beloit sits in. All-time county record high 102.8°F (2012-07-07); record low -31.8°F (1951-01-30). Source: NOAA / National Weather Service.