Sunapee, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 33.5 °F (low) to 55.2 °F (high). Annual precipitation averages 45.6 Inches. Sunapee is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 8.7 °F | 28.8 °F | 3.04 in. |
| February | 10.1 °F | 31.8 °F | 2.74 in. |
| March | 18.8 °F | 39.6 °F | 3.28 in. |
| April | 31.3 °F | 54.1 °F | 3.61 in. |
| May | 41.8 °F | 66.8 °F | 3.61 in. |
| June | 51.8 °F | 75.1 °F | 4.42 in. |
| July | 56.8 °F | 79.7 °F | 4.42 in. |
| August | 54.3 °F | 78.2 °F | 3.84 in. |
| September | 46.0 °F | 70.9 °F | 3.91 in. |
| October | 37.1 °F | 57.8 °F | 5.21 in. |
| November | 26.9 °F | 45.3 °F | 3.59 in. |
| December | 18.4 °F | 34.6 °F | 3.89 in. |
| Annual | 33.5 °F | 55.2 °F | 45.56 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | Over 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 | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |