The official National Weather Service forecast for Fairmont — 40.6369°N, 97.5853°W, 17.1 miles from I-80.
| Fillmore County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 36 | 40 | 53 | 64 | 74 | 84 | 88 | 85 | 80 | 66 | 53 | 39 | 64 |
| Avg low °F | 15 | 18 | 29 | 39 | 50 | 61 | 65 | 63 | 54 | 42 | 29 | 19 | 40 |
| Precip in | 0.6 | 0.8 | 1.5 | 2.3 | 4.6 | 4.0 | 3.4 | 3.4 | 2.5 | 2.2 | 1.2 | 0.9 | 27.4 |
1996–2025 normals for Fillmore County — the climate division Fairmont sits in. All-time county record high 109.6°F (1954-07-13); record low -27.3°F (2021-02-16). Source: NOAA / National Weather Service.