Greenfield, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 35.4 °F (low) to 56.6 °F (high). Annual precipitation averages 48.9 Inches. Greenfield is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 12.4 °F | 31.0 °F | 3.54 in. |
| February | 13.6 °F | 34.1 °F | 3.28 in. |
| March | 21.5 °F | 42.0 °F | 4.04 in. |
| April | 32.5 °F | 55.7 °F | 3.92 in. |
| May | 43.4 °F | 66.8 °F | 3.86 in. |
| June | 52.9 °F | 75.6 °F | 4.4 in. |
| July | 58.1 °F | 80.6 °F | 4.13 in. |
| August | 56.2 °F | 79.0 °F | 4.07 in. |
| September | 48.6 °F | 71.8 °F | 4.19 in. |
| October | 37.8 °F | 58.9 °F | 5.21 in. |
| November | 28.5 °F | 47.3 °F | 3.89 in. |
| December | 19.1 °F | 36.6 °F | 4.39 in. |
| Annual | 35.4 °F | 56.6 °F | 48.92 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |