Deer Isle, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 38.4 °F (low) to 53.4 °F (high). Annual precipitation averages 50.5 Inches. 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 | 17.1 °F | 32.0 °F | 4.2 in. |
| February | 18.5 °F | 33.4 °F | 3.57 in. |
| March | 25.5 °F | 39.7 °F | 4.37 in. |
| April | 34.8 °F | 49.8 °F | 4.51 in. |
| May | 43.5 °F | 59.7 °F | 3.86 in. |
| June | 52.1 °F | 68.1 °F | 4.21 in. |
| July | 58.0 °F | 74.2 °F | 3.25 in. |
| August | 57.8 °F | 74.1 °F | 3.15 in. |
| September | 52.2 °F | 67.8 °F | 4.09 in. |
| October | 42.9 °F | 57.1 °F | 5.43 in. |
| November | 34.1 °F | 47.1 °F | 4.87 in. |
| December | 24.3 °F | 38.0 °F | 4.94 in. |
| Annual | 38.4 °F | 53.4 °F | 50.45 in. |
| 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 : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |