Greenbush, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.3 °C (low) to 12.3 °C (high). Annual precipitation averages 1129.3 Millimeters. Greenbush 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 | -14.5 °C | -2.7 °C | 86.87 mm |
| February | -13.7 °C | -0.9 °C | 70.36 mm |
| March | -7.3 °C | 3.9 °C | 87.12 mm |
| April | -0.7 °C | 11 °C | 92.71 mm |
| May | 5.2 °C | 18.1 °C | 88.65 mm |
| June | 10.2 °C | 23.3 °C | 104.65 mm |
| July | 13.7 °C | 26.3 °C | 86.11 mm |
| August | 12.5 °C | 25.8 °C | 86.36 mm |
| September | 8.2 °C | 21.3 °C | 92.71 mm |
| October | 2.2 °C | 13.8 °C | 119.38 mm |
| November | -2.7 °C | 7.1 °C | 103.38 mm |
| December | -9.2 °C | 0.9 °C | 111 mm |
| Annual | 0.3 °C | 12.3 °C | 1129.3 mm |
| 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 : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |