The official National Weather Service forecast for Fort Pierre — 44.3536°N, 100.3737°W, 30.6 miles from I-90.
| Stanley County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 31 | 35 | 47 | 59 | 70 | 81 | 89 | 87 | 79 | 62 | 47 | 34 | 60 |
| Avg low °F | 10 | 12 | 22 | 32 | 44 | 55 | 61 | 59 | 49 | 36 | 23 | 13 | 35 |
| Precip in | 0.4 | 0.5 | 0.9 | 2.0 | 3.0 | 3.1 | 2.3 | 2.3 | 1.6 | 1.5 | 0.5 | 0.5 | 18.6 |
1996–2025 normals for Stanley County — the climate division Fort Pierre sits in. All-time county record high 113.7°F (2006-07-16); record low -32.8°F (1994-02-09). Source: NOAA / National Weather Service.