Foresthill, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 8.8 °C (low) to 20.3 °C (high). Annual precipitation averages 1353.8 Millimeters. Foresthill is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.3 °C | 11.2 °C | 238.76 mm |
| February | 2.2 °C | 11.9 °C | 230.63 mm |
| March | 3.4 °C | 14.5 °C | 196.85 mm |
| April | 4.9 °C | 17.3 °C | 116.08 mm |
| May | 8.8 °C | 22 °C | 71.37 mm |
| June | 13.6 °C | 27.7 °C | 20.57 mm |
| July | 17.9 °C | 32.1 °C | 0 mm |
| August | 18.3 °C | 31.9 °C | 2.54 mm |
| September | 15 °C | 28.6 °C | 14.73 mm |
| October | 10.7 °C | 21.8 °C | 69.34 mm |
| November | 5.7 °C | 14.6 °C | 137.92 mm |
| December | 2.3 °C | 10.2 °C | 255.02 mm |
| Annual | 8.8 °C | 20.3 °C | 1353.81 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 30-40 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°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 |