The official National Weather Service forecast for Chinook — 48.59°N, 109.2313°W, 120.2 miles from I-15.
| Blaine County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 30 | 31 | 42 | 55 | 65 | 74 | 85 | 83 | 72 | 57 | 42 | 31 | 56 |
| Avg low °F | 8 | 10 | 19 | 29 | 39 | 48 | 54 | 52 | 43 | 31 | 20 | 11 | 30 |
| Precip in | 0.5 | 0.5 | 0.7 | 1.2 | 2.4 | 2.8 | 1.4 | 1.2 | 1.3 | 0.9 | 0.6 | 0.6 | 14.1 |
1996–2025 normals for Blaine County — the climate division Chinook sits in. All-time county record high 104.8°F (1961-08-06); record low -45.4°F (1954-01-20). Source: NOAA / National Weather Service.