Clay, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 9.3 °C (low) to 23.7 °C (high). Annual precipitation averages 514.9 Millimeters. 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 | 4 °C | 13.3 °C | 99.31 mm |
| February | 5.2 °C | 16.1 °C | 91.69 mm |
| March | 6.8 °C | 18.9 °C | 76.71 mm |
| April | 8.1 °C | 21.9 °C | 43.69 mm |
| May | 10.9 °C | 26.4 °C | 25.91 mm |
| June | 13.5 °C | 30.8 °C | 5.08 mm |
| July | 15.1 °C | 34 °C | 0.51 mm |
| August | 14.9 °C | 33.5 °C | 1.27 mm |
| September | 13.5 °C | 31.4 °C | 3.05 mm |
| October | 10 °C | 25.7 °C | 23.88 mm |
| November | 5.9 °C | 18.3 °C | 49.53 mm |
| December | 3.6 °C | 13.5 °C | 94.23 mm |
| Annual | 9.3 °C | 23.7 °C | 514.86 mm |
| 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 : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9b : -3.9°C to -1.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |