Jamestown, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 47.4 °F (low) to 74.2 °F (high). Annual precipitation averages 29.8 Inches. Jamestown is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 36.8 °F | 56.3 °F | 5.96 in. |
| February | 38.1 °F | 59.3 °F | 5.12 in. |
| March | 40.9 °F | 64.0 °F | 4.55 in. |
| April | 43.5 °F | 68.4 °F | 2.55 in. |
| May | 49.0 °F | 77.9 °F | 1.44 in. |
| June | 55.2 °F | 87.5 °F | 0.34 in. |
| July | 61.4 °F | 94.7 °F | 0.03 in. |
| August | 60.5 °F | 93.8 °F | 0.07 in. |
| September | 56.5 °F | 88.8 °F | 0.18 in. |
| October | 48.8 °F | 78.0 °F | 1.46 in. |
| November | 41.2 °F | 65.0 °F | 2.87 in. |
| December | 36.4 °F | 56.2 °F | 5.23 in. |
| Annual | 47.4 °F | 74.2 °F | 29.8 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 9a : 20°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 9a : 20°F to 25°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |