Hermon, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 33.9 °F (low) to 54.3 °F (high). Annual precipitation averages 45.9 Inches. Hermon is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.4 °F | 27.3 °F | 3.38 in. |
| February | 9.1 °F | 30.5 °F | 3.06 in. |
| March | 20.0 °F | 39.1 °F | 3.87 in. |
| April | 31.7 °F | 52.1 °F | 4.02 in. |
| May | 42.4 °F | 64.7 °F | 3.47 in. |
| June | 51.8 °F | 73.6 °F | 4.03 in. |
| July | 57.9 °F | 79.3 °F | 3.28 in. |
| August | 56.0 °F | 78.3 °F | 3.38 in. |
| September | 48.2 °F | 70.4 °F | 3.87 in. |
| October | 37.4 °F | 57.2 °F | 4.84 in. |
| November | 28.2 °F | 44.9 °F | 4.08 in. |
| December | 16.5 °F | 33.6 °F | 4.6 in. |
| Annual | 33.9 °F | 54.3 °F | 45.88 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°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 |