Plymouth, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 33.4 °F (low) to 54.6 °F (high). Annual precipitation averages 45 Inches. Plymouth 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 | 7.0 °F | 27.3 °F | 3.39 in. |
| February | 8.5 °F | 30.7 °F | 2.84 in. |
| March | 19.3 °F | 39.5 °F | 3.52 in. |
| April | 31.2 °F | 52.8 °F | 3.83 in. |
| May | 42.1 °F | 65.5 °F | 3.54 in. |
| June | 51.5 °F | 74.2 °F | 4.17 in. |
| July | 57.4 °F | 79.7 °F | 3.36 in. |
| August | 55.6 °F | 78.5 °F | 3.51 in. |
| September | 47.7 °F | 70.9 °F | 3.69 in. |
| October | 36.9 °F | 57.7 °F | 4.84 in. |
| November | 27.5 °F | 44.9 °F | 4.14 in. |
| December | 15.9 °F | 33.6 °F | 4.16 in. |
| Annual | 33.4 °F | 54.6 °F | 44.99 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 4b : -25°F to -20°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |