Wilton, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 49 °F (low) to 74.4 °F (high). Annual precipitation averages 20.3 Inches. Wilton is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Jan. 21 - Jan. 31 through the first frost around Jan. 1 - Jan. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 39.4 °F | 55.6 °F | 3.89 in. |
| February | 41.5 °F | 60.8 °F | 3.87 in. |
| March | 44.5 °F | 65.9 °F | 2.98 in. |
| April | 47.0 °F | 71.4 °F | 1.62 in. |
| May | 52.1 °F | 79.5 °F | 0.97 in. |
| June | 56.8 °F | 87.3 °F | 0.19 in. |
| July | 59.5 °F | 92.8 °F | 0.0 in. |
| August | 59.1 °F | 91.8 °F | 0.03 in. |
| September | 56.5 °F | 88.4 °F | 0.12 in. |
| October | 50.3 °F | 78.2 °F | 1.01 in. |
| November | 42.8 °F | 64.7 °F | 1.89 in. |
| December | 38.8 °F | 56.0 °F | 3.72 in. |
| Annual | 49 °F | 74.4 °F | 20.29 in. |
| Average First Frost Date | Jan. 1 - Jan. 10 |
| Average Last Frost Date | Jan. 21 - Jan. 31 |
| Average Days With Frost | Frost Rare |
| 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 |