Clearlake, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 44.5 °F (low) to 72.2 °F (high). Annual precipitation averages 30.9 Inches. 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 | 35.1 °F | 56.0 °F | 6.54 in. |
| February | 36.0 °F | 58.7 °F | 6.21 in. |
| March | 38.2 °F | 62.7 °F | 4.08 in. |
| April | 41.1 °F | 67.0 °F | 1.91 in. |
| May | 46.6 °F | 74.8 °F | 1.26 in. |
| June | 52.9 °F | 84.0 °F | 0.23 in. |
| July | 57.8 °F | 91.9 °F | 0.0 in. |
| August | 56.4 °F | 91.0 °F | 0.03 in. |
| September | 52.1 °F | 86.3 °F | 0.12 in. |
| October | 45.4 °F | 75.7 °F | 1.3 in. |
| November | 38.2 °F | 63.2 °F | 2.87 in. |
| December | 34.7 °F | 55.6 °F | 6.33 in. |
| Annual | 44.5 °F | 72.2 °F | 30.88 in. |
| 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 : 20°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |