The official National Weather Service forecast for Hiawatha — 39.8525°N, 95.5358°W, 23.4 miles from I-29.
| Brown County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 37 | 42 | 54 | 65 | 75 | 84 | 88 | 86 | 80 | 68 | 54 | 41 | 64 |
| Avg low °F | 17 | 20 | 32 | 41 | 53 | 63 | 67 | 65 | 56 | 43 | 31 | 21 | 42 |
| Precip in | 0.8 | 1.1 | 1.9 | 3.4 | 4.9 | 5.0 | 4.1 | 4.0 | 3.1 | 2.9 | 1.8 | 1.2 | 34.2 |
1996–2025 normals for Brown County — the climate division Hiawatha sits in. All-time county record high 107.7°F (1980-07-15); record low -24.6°F (1989-12-23). Source: NOAA / National Weather Service.