The official National Weather Service forecast for Williams — 39.1546°N, 122.1494°W, population 5,558, 4.1 miles from I-5. Forecasts here are written by NWS STO, this county’s forecast office.
| Colusa County | J | F | M | A | M | J | J | A | S | O | N | D | Year |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high °F | 57 | 60 | 65 | 72 | 81 | 90 | 96 | 94 | 89 | 78 | 64 | 56 | 75 |
| Avg low °F | 38 | 40 | 42 | 45 | 52 | 59 | 62 | 61 | 57 | 49 | 42 | 38 | 49 |
| Precip in | 4.4 | 4.6 | 3.0 | 1.5 | 0.9 | 0.2 | 0.0 | 0.0 | 0.2 | 1.2 | 2.8 | 5.1 | 23.9 |
1996–2025 normals for Colusa County — the climate division Williams sits in. All-time county record high 113.3°F (1972-07-15); record low 15.3°F (1990-12-23). Source: NOAA / National Weather Service.