Richmond, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.9 °C (low) to 13.7 °C (high). Annual precipitation averages 1233.2 Millimeters. Richmond 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 Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.1 °C | -0.5 °C | 92.71 mm |
| February | -10.1 °C | 1.3 °C | 79.76 mm |
| March | -5.8 °C | 5.6 °C | 94.74 mm |
| April | 0.5 °C | 13 °C | 95 mm |
| May | 6.2 °C | 19.7 °C | 97.28 mm |
| June | 11.6 °C | 24.4 °C | 116.59 mm |
| July | 14.5 °C | 27.2 °C | 108.71 mm |
| August | 13.1 °C | 26.2 °C | 109.47 mm |
| September | 8.8 °C | 21.8 °C | 109.98 mm |
| October | 3.3 °C | 14.9 °C | 128.02 mm |
| November | -1.7 °C | 8.4 °C | 94.74 mm |
| December | -7.1 °C | 2.5 °C | 106.17 mm |
| Annual | 1.9 °C | 13.7 °C | 1233.17 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 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 | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |