Penn Valley, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 48.2 °F (low) to 72.6 °F (high). Annual precipitation averages 39.9 Inches. Penn Valley is located in USDA Plant Hardiness Zone 9b. 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 | 37.9 °F | 55.5 °F | 7.19 in. |
| February | 39.1 °F | 58.5 °F | 6.6 in. |
| March | 41.6 °F | 62.6 °F | 6.2 in. |
| April | 44.1 °F | 67.2 °F | 3.29 in. |
| May | 50.1 °F | 75.8 °F | 1.85 in. |
| June | 56.1 °F | 85.0 °F | 0.52 in. |
| July | 61.5 °F | 92.6 °F | 0.02 in. |
| August | 60.9 °F | 92.0 °F | 0.09 in. |
| September | 57.2 °F | 87.1 °F | 0.29 in. |
| October | 50.1 °F | 76.6 °F | 1.94 in. |
| November | 42.2 °F | 63.0 °F | 4.09 in. |
| December | 37.4 °F | 54.7 °F | 7.77 in. |
| Annual | 48.2 °F | 72.6 °F | 39.85 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 9b : 25°F to 20°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 |