Kelseyville, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 5.7 °C (low) to 22.9 °C (high). Annual precipitation averages 703.8 Millimeters. Kelseyville is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 21 - Nov. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.3 °C | 13.2 °C | 143.51 mm |
| February | 1.7 °C | 15.1 °C | 137.67 mm |
| March | 2.7 °C | 17.6 °C | 86.11 mm |
| April | 4.1 °C | 20.3 °C | 49.02 mm |
| May | 6.7 °C | 24.9 °C | 29.46 mm |
| June | 9.5 °C | 30 °C | 5.08 mm |
| July | 12.4 °C | 34.6 °C | 0.76 mm |
| August | 11.7 °C | 33.9 °C | 1.27 mm |
| September | 9.1 °C | 30.9 °C | 2.54 mm |
| October | 5.8 °C | 24.5 °C | 32.77 mm |
| November | 2.7 °C | 16.8 °C | 68.07 mm |
| December | 0.7 °C | 12.8 °C | 147.57 mm |
| Annual | 5.7 °C | 22.9 °C | 703.83 mm |
| Average First Frost Date | Nov. 21 - Nov. 30 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°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 |