The official National Weather Service forecast for Missouri Valley — 41.5564°N, 95.8878°W, 1.8 miles from I-29.
| Harrison County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 31 | 36 | 50 | 62 | 73 | 83 | 86 | 83 | 78 | 65 | 50 | 36 | 61 |
| Avg low °F | 13 | 16 | 28 | 38 | 50 | 61 | 64 | 62 | 54 | 41 | 28 | 17 | 39 |
| Precip in | 0.8 | 0.9 | 1.8 | 3.1 | 4.9 | 4.7 | 3.6 | 4.3 | 3.0 | 2.3 | 1.3 | 1.2 | 31.9 |
1996–2025 normals for Harrison County — the climate division Missouri Valley sits in. All-time county record high 104.0°F (1995-07-13); record low -25.5°F (2021-02-16). Source: NOAA / National Weather Service.