Etna, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.6 °C (low) to 12.3 °C (high). Annual precipitation averages 1158.2 Millimeters. Etna is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -14 °C | -2.9 °C | 87.38 mm |
| February | -13.2 °C | -0.9 °C | 73.91 mm |
| March | -7.3 °C | 3.9 °C | 92.2 mm |
| April | -0.7 °C | 11.2 °C | 99.06 mm |
| May | 5.4 °C | 18.3 °C | 91.19 mm |
| June | 10.8 °C | 23.2 °C | 105.92 mm |
| July | 14.1 °C | 26.2 °C | 85.85 mm |
| August | 13 °C | 25.6 °C | 88.9 mm |
| September | 8.6 °C | 21.3 °C | 94.74 mm |
| October | 2.6 °C | 13.9 °C | 124.71 mm |
| November | -2.6 °C | 6.9 °C | 105.41 mm |
| December | -9 °C | 0.6 °C | 108.97 mm |
| Annual | 0.6 °C | 12.3 °C | 1158.24 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |