The official National Weather Service forecast for Miles City — 46.4083°N, 105.8406°W, population 9,227, 1.5 miles from I-94.
| Custer County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 31 | 34 | 47 | 58 | 68 | 78 | 89 | 87 | 76 | 59 | 45 | 33 | 59 |
| Avg low °F | 10 | 12 | 22 | 31 | 41 | 51 | 58 | 55 | 45 | 33 | 21 | 11 | 32 |
| Precip in | 0.4 | 0.4 | 0.6 | 1.5 | 2.9 | 2.4 | 1.6 | 1.2 | 1.2 | 1.2 | 0.4 | 0.4 | 14.2 |
1996–2025 normals for Custer County — the climate division Miles City sits in. All-time county record high 113.6°F (2026-07-13); record low -38.7°F (1989-12-22). Source: NOAA / National Weather Service.