Boothbay Harbor, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 39.3 °F (low) to 54.5 °F (high). Annual precipitation averages 51.1 Inches. Boothbay Harbor is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 18.0 °F | 31.6 °F | 4.14 in. |
| February | 19.2 °F | 34.0 °F | 3.88 in. |
| March | 25.8 °F | 40.7 °F | 4.72 in. |
| April | 35.0 °F | 51.4 °F | 4.48 in. |
| May | 44.7 °F | 61.6 °F | 3.69 in. |
| June | 53.7 °F | 70.3 °F | 4.5 in. |
| July | 59.7 °F | 76.3 °F | 3.66 in. |
| August | 59.2 °F | 76.1 °F | 3.16 in. |
| September | 52.6 °F | 69.3 °F | 4.05 in. |
| October | 43.7 °F | 57.9 °F | 5.35 in. |
| November | 34.9 °F | 47.6 °F | 4.52 in. |
| December | 24.9 °F | 37.6 °F | 4.97 in. |
| Annual | 39.3 °F | 54.5 °F | 51.12 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |