Amherst, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.8 °C (low) to 14.8 °C (high). Annual precipitation averages 1199.4 Millimeters. Amherst is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.1 °C | 0.8 °C | 85.34 mm |
| February | -9.3 °C | 2.4 °C | 81.28 mm |
| March | -4.7 °C | 6.8 °C | 97.28 mm |
| April | 1.3 °C | 14.2 °C | 102.11 mm |
| May | 7.4 °C | 20.3 °C | 94.49 mm |
| June | 12.6 °C | 25.3 °C | 112.52 mm |
| July | 15.6 °C | 28.2 °C | 97.54 mm |
| August | 14.6 °C | 27.3 °C | 95.25 mm |
| September | 10.3 °C | 23.2 °C | 102.87 mm |
| October | 3.7 °C | 16.1 °C | 123.7 mm |
| November | -1.4 °C | 9.7 °C | 96.27 mm |
| December | -6.4 °C | 3.8 °C | 110.74 mm |
| Annual | 2.8 °C | 14.8 °C | 1199.39 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| 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 |