The official National Weather Service forecast for Altamont — 44.8397°N, 96.6895°W, 11.5 miles from I-29.
| Deuel County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 22 | 26 | 39 | 53 | 67 | 77 | 82 | 79 | 72 | 57 | 41 | 27 | 54 |
| Avg low °F | 5 | 7 | 20 | 32 | 44 | 56 | 60 | 57 | 49 | 36 | 23 | 11 | 33 |
| Precip in | 0.6 | 0.7 | 1.3 | 2.6 | 3.5 | 3.7 | 3.3 | 3.5 | 2.7 | 2.4 | 1.0 | 1.0 | 26.3 |
1996–2025 normals for Deuel County — the climate division Altamont sits in. All-time county record high 102.4°F (1988-08-01); record low -35.6°F (1994-02-09). Source: NOAA / National Weather Service.