Hallowell, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 36 °F (low) to 55.6 °F (high). Annual precipitation averages 46.7 Inches. Hallowell is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 10.7 °F | 29.7 °F | 3.48 in. |
| February | 12.4 °F | 32.7 °F | 2.97 in. |
| March | 22.3 °F | 41.1 °F | 3.7 in. |
| April | 33.1 °F | 53.6 °F | 4.17 in. |
| May | 43.8 °F | 65.0 °F | 3.42 in. |
| June | 53.4 °F | 73.9 °F | 4.26 in. |
| July | 59.4 °F | 79.8 °F | 3.3 in. |
| August | 58.0 °F | 79.0 °F | 3.47 in. |
| September | 50.6 °F | 71.5 °F | 3.9 in. |
| October | 39.5 °F | 58.9 °F | 5.36 in. |
| November | 29.7 °F | 46.7 °F | 4.39 in. |
| December | 19.0 °F | 35.8 °F | 4.26 in. |
| Annual | 36 °F | 55.6 °F | 46.68 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |