Clearlake, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 7 °C (low) to 22.4 °C (high). Annual precipitation averages 784.3 Millimeters. Clearlake 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. 21 - Nov. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.7 °C | 13.3 °C | 166.12 mm |
| February | 2.2 °C | 14.8 °C | 157.73 mm |
| March | 3.4 °C | 17.1 °C | 103.63 mm |
| April | 5.1 °C | 19.4 °C | 48.51 mm |
| May | 8.1 °C | 23.8 °C | 32 mm |
| June | 11.6 °C | 28.9 °C | 5.84 mm |
| July | 14.3 °C | 33.3 °C | 0 mm |
| August | 13.6 °C | 32.8 °C | 0.76 mm |
| September | 11.2 °C | 30.2 °C | 3.05 mm |
| October | 7.4 °C | 24.3 °C | 33.02 mm |
| November | 3.4 °C | 17.3 °C | 72.9 mm |
| December | 1.5 °C | 13.1 °C | 160.78 mm |
| Annual | 7 °C | 22.4 °C | 784.34 mm |
| Average First Frost Date | Nov. 21 - Nov. 30 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |