Deer Isle, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.6 °C (low) to 11.9 °C (high). Annual precipitation averages 1281.4 Millimeters. Deer Isle is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.3 °C | 0 °C | 106.68 mm |
| February | -7.5 °C | 0.8 °C | 90.68 mm |
| March | -3.6 °C | 4.3 °C | 111 mm |
| April | 1.6 °C | 9.9 °C | 114.55 mm |
| May | 6.4 °C | 15.4 °C | 98.04 mm |
| June | 11.2 °C | 20.1 °C | 106.93 mm |
| July | 14.4 °C | 23.4 °C | 82.55 mm |
| August | 14.3 °C | 23.4 °C | 80.01 mm |
| September | 11.2 °C | 19.9 °C | 103.89 mm |
| October | 6.1 °C | 13.9 °C | 137.92 mm |
| November | 1.2 °C | 8.4 °C | 123.7 mm |
| December | -4.3 °C | 3.3 °C | 125.48 mm |
| Annual | 3.6 °C | 11.9 °C | 1281.43 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |