Etna, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 3.1 °C (low) to 19.4 °C (high). Annual precipitation averages 562.1 Millimeters. Etna is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.3 °C | 7.8 °C | 107.19 mm |
| February | -1.6 °C | 10.8 °C | 79.25 mm |
| March | -0.4 °C | 13.8 °C | 60.45 mm |
| April | 1.3 °C | 17.3 °C | 31.24 mm |
| May | 4.6 °C | 22.5 °C | 25.15 mm |
| June | 7.4 °C | 27.3 °C | 14.99 mm |
| July | 11.1 °C | 32.8 °C | 11.94 mm |
| August | 10.3 °C | 32.3 °C | 5.33 mm |
| September | 7.3 °C | 28.7 °C | 7.62 mm |
| October | 2.9 °C | 21.1 °C | 39.88 mm |
| November | -0.6 °C | 12 °C | 69.6 mm |
| December | -2.6 °C | 6.8 °C | 109.47 mm |
| Annual | 3.1 °C | 19.4 °C | 562.11 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |