Epsom, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.1 °C (low) to 14 °C (high). Annual precipitation averages 1162.8 Millimeters. Epsom 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 | -10.6 °C | -0.4 °C | 76.71 mm |
| February | -10 °C | 1.4 °C | 79.76 mm |
| March | -5.5 °C | 5.7 °C | 92.96 mm |
| April | 0.4 °C | 13.4 °C | 95.25 mm |
| May | 6.6 °C | 19.8 °C | 96.52 mm |
| June | 11.8 °C | 24.7 °C | 108.97 mm |
| July | 14.7 °C | 27.7 °C | 101.6 mm |
| August | 13.8 °C | 26.6 °C | 95.5 mm |
| September | 9.3 °C | 22.6 °C | 101.09 mm |
| October | 3.4 °C | 15.3 °C | 122.43 mm |
| November | -1.9 °C | 8.5 °C | 88.14 mm |
| December | -7.1 °C | 2.6 °C | 103.89 mm |
| Annual | 2.1 °C | 14 °C | 1162.82 mm |
| 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 : -26.1°C to -23.3°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 |