The official National Weather Service forecast for Hamilton — 46.2469°N, 114.1604°W, population 6,870, 40 miles from I-90.
| Ravalli County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 31 | 34 | 43 | 50 | 58 | 67 | 79 | 76 | 66 | 51 | 38 | 30 | 52 |
| Avg low °F | 17 | 17 | 22 | 27 | 34 | 40 | 46 | 45 | 39 | 30 | 22 | 16 | 30 |
| Precip in | 3.0 | 2.8 | 2.6 | 2.4 | 2.8 | 2.7 | 1.0 | 1.1 | 1.5 | 2.3 | 2.9 | 3.5 | 28.6 |
1996–2025 normals for Ravalli County — the climate division Hamilton sits in. All-time county record high 93.9°F (2002-07-12); record low -31.9°F (1979-01-01). Source: NOAA / National Weather Service.