Williams, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 9.4 °C (low) to 24 °C (high). Annual precipitation averages 426.7 Millimeters. 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 | 3.8 °C | 13.4 °C | 90.42 mm |
| February | 5.1 °C | 16.3 °C | 81.03 mm |
| March | 6.4 °C | 19.4 °C | 53.59 mm |
| April | 7.8 °C | 22.8 °C | 28.45 mm |
| May | 11.8 °C | 27.2 °C | 15.24 mm |
| June | 14.8 °C | 31.3 °C | 4.32 mm |
| July | 16.1 °C | 33.8 °C | 0.25 mm |
| August | 15.2 °C | 33.3 °C | 1.27 mm |
| September | 13.2 °C | 31.7 °C | 4.32 mm |
| October | 9.7 °C | 26.5 °C | 20.07 mm |
| November | 5.7 °C | 18.5 °C | 42.16 mm |
| December | 3.4 °C | 13.4 °C | 85.6 mm |
| Annual | 9.4 °C | 24 °C | 426.72 mm |
| 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 : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9b : -3.9°C to -1.1°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |