Greenfield, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.6 °C (low) to 14.9 °C (high). Annual precipitation averages 1247.9 Millimeters. Greenfield is located in USDA Plant Hardiness Zone 6a. 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 | -10.4 °C | 0.5 °C | 90.42 mm |
| February | -9.7 °C | 2.4 °C | 79.76 mm |
| March | -4.9 °C | 7 °C | 94.74 mm |
| April | 1.1 °C | 14.2 °C | 98.3 mm |
| May | 7.1 °C | 20.7 °C | 99.31 mm |
| June | 12.5 °C | 25.6 °C | 116.84 mm |
| July | 15.4 °C | 28.4 °C | 107.7 mm |
| August | 14.4 °C | 27.5 °C | 112.52 mm |
| September | 10 °C | 23.3 °C | 119.13 mm |
| October | 3.6 °C | 16.1 °C | 124.46 mm |
| November | -1.7 °C | 9.4 °C | 93.73 mm |
| December | -6.4 °C | 3.5 °C | 111 mm |
| Annual | 2.6 °C | 14.9 °C | 1247.91 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |