Penn Valley, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 9 °C (low) to 22.5 °C (high). Annual precipitation averages 1012.2 Millimeters. 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 | 3.3 °C | 13.1 °C | 182.63 mm |
| February | 3.9 °C | 14.7 °C | 167.64 mm |
| March | 5.3 °C | 17 °C | 157.48 mm |
| April | 6.7 °C | 19.6 °C | 83.57 mm |
| May | 10.1 °C | 24.3 °C | 46.99 mm |
| June | 13.4 °C | 29.4 °C | 13.21 mm |
| July | 16.4 °C | 33.7 °C | 0.51 mm |
| August | 16.1 °C | 33.3 °C | 2.29 mm |
| September | 14 °C | 30.6 °C | 7.37 mm |
| October | 10.1 °C | 24.8 °C | 49.28 mm |
| November | 5.7 °C | 17.2 °C | 103.89 mm |
| December | 3 °C | 12.6 °C | 197.36 mm |
| Annual | 9 °C | 22.5 °C | 1012.22 mm |
| 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 : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9a : -6.7°C to -3.9°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |