Northeast Harbor, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.8 °C (low) to 12 °C (high). Annual precipitation averages 1370.3 Millimeters. Northeast Harbor 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 | -7.2 °C | -0.3 °C | 118.62 mm |
| February | -6.8 °C | 0.5 °C | 98.81 mm |
| March | -3.7 °C | 4.1 °C | 121.92 mm |
| April | 1.4 °C | 9.9 °C | 115.82 mm |
| May | 6.4 °C | 15.8 °C | 112.52 mm |
| June | 11.1 °C | 20.9 °C | 107.95 mm |
| July | 14.4 °C | 24.2 °C | 82.3 mm |
| August | 14.3 °C | 23.9 °C | 77.47 mm |
| September | 11.1 °C | 20 °C | 104.65 mm |
| October | 6.6 °C | 13.9 °C | 145.03 mm |
| November | 1.7 °C | 8.2 °C | 143 mm |
| December | -3.6 °C | 3 °C | 142.24 mm |
| Annual | 3.8 °C | 12 °C | 1370.33 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 |