Clay, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 48.7 °F (low) to 74.6 °F (high). Annual precipitation averages 20.3 Inches. Clay is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Feb. 1 - Feb. 10 through the first frost around Dec. 21 - Dec. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 39.2 °F | 55.9 °F | 3.91 in. |
| February | 41.3 °F | 61.0 °F | 3.61 in. |
| March | 44.3 °F | 66.0 °F | 3.02 in. |
| April | 46.6 °F | 71.5 °F | 1.72 in. |
| May | 51.6 °F | 79.5 °F | 1.02 in. |
| June | 56.3 °F | 87.4 °F | 0.2 in. |
| July | 59.1 °F | 93.2 °F | 0.02 in. |
| August | 58.9 °F | 92.3 °F | 0.05 in. |
| September | 56.3 °F | 88.5 °F | 0.12 in. |
| October | 50.0 °F | 78.2 °F | 0.94 in. |
| November | 42.7 °F | 64.9 °F | 1.95 in. |
| December | 38.5 °F | 56.3 °F | 3.71 in. |
| Annual | 48.7 °F | 74.6 °F | 20.27 in. |
| Average First Frost Date | Dec. 21 - Dec. 31 |
| Average Last Frost Date | Feb. 1 - Feb. 10 |
| 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 | Normal |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |