Winchester, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 35.6 °F (low) to 58 °F (high). Annual precipitation averages 47.2 Inches. Winchester is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 11.9 °F | 31.8 °F | 3.48 in. |
| February | 13.2 °F | 35.1 °F | 3.04 in. |
| March | 22.0 °F | 43.4 °F | 3.56 in. |
| April | 32.9 °F | 56.8 °F | 3.61 in. |
| May | 44.1 °F | 68.8 °F | 3.73 in. |
| June | 53.5 °F | 77.4 °F | 4.42 in. |
| July | 58.7 °F | 82.6 °F | 4.27 in. |
| August | 56.9 °F | 81.0 °F | 4.26 in. |
| September | 48.9 °F | 73.5 °F | 4.12 in. |
| October | 37.6 °F | 60.4 °F | 4.93 in. |
| November | 28.3 °F | 48.0 °F | 3.61 in. |
| December | 19.1 °F | 37.1 °F | 4.13 in. |
| Annual | 35.6 °F | 58 °F | 47.16 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 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 |