The official National Weather Service forecast for Fort Madison — 40.6298°N, 91.3152°W, population 10,278, 71.4 miles from I-74.
| Lee County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 33 | 38 | 51 | 63 | 73 | 82 | 86 | 84 | 78 | 65 | 51 | 38 | 62 |
| Avg low °F | 16 | 20 | 31 | 41 | 52 | 62 | 66 | 64 | 56 | 44 | 32 | 22 | 42 |
| Precip in | 1.6 | 1.8 | 2.7 | 3.8 | 5.0 | 5.0 | 4.1 | 3.6 | 3.5 | 3.2 | 2.0 | 1.9 | 38.2 |
1996–2025 normals for Lee County — the climate division Fort Madison sits in. All-time county record high 105.0°F (2012-07-24); record low -20.2°F (1989-12-23). Source: NOAA / National Weather Service.