Greenville, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 30.6 °F (low) to 50.4 °F (high). Annual precipitation averages 46.3 Inches. Greenville is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3.2 °F | 22.8 °F | 3.19 in. |
| February | 3.6 °F | 25.7 °F | 2.77 in. |
| March | 13.9 °F | 35.0 °F | 3.1 in. |
| April | 27.9 °F | 47.5 °F | 3.76 in. |
| May | 39.9 °F | 61.7 °F | 3.81 in. |
| June | 49.8 °F | 70.5 °F | 4.47 in. |
| July | 55.3 °F | 76.0 °F | 4.13 in. |
| August | 53.4 °F | 74.9 °F | 4.0 in. |
| September | 45.7 °F | 67.4 °F | 3.59 in. |
| October | 35.5 °F | 53.5 °F | 5.14 in. |
| November | 25.6 °F | 40.5 °F | 3.91 in. |
| December | 12.9 °F | 29.2 °F | 4.39 in. |
| Annual | 30.6 °F | 50.4 °F | 46.26 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |