Sanbornton, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.6 °C (low) to 13.3 °C (high). Annual precipitation averages 1219.7 Millimeters. Sanbornton 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.6 °C | -1.5 °C | 80.52 mm |
| February | -11.2 °C | 0.3 °C | 75.69 mm |
| March | -6.2 °C | 5.1 °C | 89.66 mm |
| April | 0.1 °C | 12.6 °C | 98.04 mm |
| May | 6.3 °C | 19.7 °C | 97.54 mm |
| June | 11.5 °C | 24.3 °C | 114.81 mm |
| July | 14.2 °C | 27.3 °C | 116.84 mm |
| August | 13.4 °C | 26.3 °C | 104.39 mm |
| September | 9.1 °C | 22 °C | 101.09 mm |
| October | 3.2 °C | 14.4 °C | 134.37 mm |
| November | -2 °C | 7.7 °C | 100.58 mm |
| December | -7.4 °C | 1.6 °C | 106.17 mm |
| Annual | 1.6 °C | 13.3 °C | 1219.7 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |