The official National Weather Service forecast for Timber Lake — 45.4291°N, 101.074°W, 105.6 miles from I-90.
| Dewey County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 28 | 31 | 44 | 57 | 68 | 80 | 87 | 85 | 77 | 59 | 44 | 31 | 58 |
| Avg low °F | 8 | 10 | 21 | 31 | 43 | 54 | 60 | 58 | 49 | 35 | 22 | 11 | 34 |
| Precip in | 0.3 | 0.5 | 0.8 | 1.8 | 3.1 | 3.2 | 2.5 | 2.3 | 1.7 | 1.5 | 0.5 | 0.5 | 18.7 |
1996–2025 normals for Dewey County — the climate division Timber Lake sits in. All-time county record high 112.1°F (2006-07-16); record low -33.1°F (1966-01-29). Source: NOAA / National Weather Service.