Sandwich, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 32.9 °F (low) to 54.8 °F (high). Annual precipitation averages 53.6 Inches. Sandwich 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 | 8.6 °F | 28.6 °F | 3.72 in. |
| February | 9.9 °F | 31.3 °F | 3.39 in. |
| March | 19.0 °F | 39.9 °F | 3.98 in. |
| April | 30.6 °F | 53.4 °F | 4.35 in. |
| May | 41.3 °F | 66.4 °F | 4.27 in. |
| June | 50.6 °F | 74.5 °F | 4.96 in. |
| July | 55.5 °F | 79.4 °F | 5.07 in. |
| August | 53.8 °F | 78.0 °F | 4.55 in. |
| September | 46.2 °F | 70.4 °F | 4.19 in. |
| October | 35.8 °F | 57.0 °F | 5.75 in. |
| November | 27.1 °F | 44.6 °F | 4.5 in. |
| December | 16.7 °F | 34.0 °F | 4.89 in. |
| Annual | 32.9 °F | 54.8 °F | 53.62 in. |
| 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 : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |