The official National Weather Service forecast for Winterset — 41.3308°N, 94.0138°W, population 5,077, 13.5 miles from I-80.
| Madison County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 31 | 36 | 49 | 62 | 72 | 82 | 85 | 83 | 78 | 64 | 50 | 36 | 61 |
| Avg low °F | 13 | 16 | 28 | 39 | 50 | 60 | 64 | 61 | 54 | 41 | 30 | 18 | 40 |
| Precip in | 0.9 | 1.2 | 2.1 | 3.4 | 5.2 | 5.0 | 3.9 | 4.0 | 3.2 | 2.8 | 1.6 | 1.4 | 34.7 |
1996–2025 normals for Madison County — the climate division Winterset sits in. All-time county record high 104.4°F (1983-08-17); record low -28.6°F (1996-02-03). Source: NOAA / National Weather Service.