Williams, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 49 °F (low) to 75.1 °F (high). Annual precipitation averages 16.8 Inches. Williams is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Feb. 11 - Feb. 20 through the first frost around Dec. 1 - Dec. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 38.9 °F | 56.1 °F | 3.56 in. |
| February | 41.1 °F | 61.4 °F | 3.19 in. |
| March | 43.6 °F | 66.9 °F | 2.11 in. |
| April | 46.1 °F | 73.0 °F | 1.12 in. |
| May | 53.2 °F | 81.0 °F | 0.6 in. |
| June | 58.7 °F | 88.3 °F | 0.17 in. |
| July | 60.9 °F | 92.8 °F | 0.01 in. |
| August | 59.3 °F | 92.0 °F | 0.05 in. |
| September | 55.8 °F | 89.1 °F | 0.17 in. |
| October | 49.5 °F | 79.7 °F | 0.79 in. |
| November | 42.2 °F | 65.3 °F | 1.66 in. |
| December | 38.2 °F | 56.1 °F | 3.37 in. |
| Annual | 49 °F | 75.1 °F | 16.8 in. |
| Average First Frost Date | Dec. 1 - Dec. 10 |
| Average Last Frost Date | Feb. 11 - Feb. 20 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9b : 25°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 9b : 25°F to 20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |