The official National Weather Service forecast for Bonesteel — 43.0764°N, 98.9445°W, 45.8 miles from I-90.
| Gregory County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 32 | 36 | 48 | 59 | 70 | 81 | 88 | 85 | 78 | 63 | 48 | 35 | 60 |
| Avg low °F | 12 | 15 | 24 | 34 | 46 | 57 | 62 | 60 | 52 | 38 | 26 | 15 | 37 |
| Precip in | 0.5 | 0.6 | 1.2 | 2.7 | 3.6 | 3.9 | 2.7 | 2.9 | 2.3 | 1.9 | 0.7 | 0.7 | 23.7 |
1996–2025 normals for Gregory County — the climate division Bonesteel sits in. All-time county record high 110.0°F (2012-08-30); record low -30.4°F (1966-01-29). Source: NOAA / National Weather Service.