Westmoreland, New Hampshire has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 35 °F (low) to 57.1 °F (high). Annual precipitation averages 46 Inches. Westmoreland 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 | 11.2 °F | 30.8 °F | 3.28 in. |
| February | 12.7 °F | 34.1 °F | 2.82 in. |
| March | 21.2 °F | 42.3 °F | 3.31 in. |
| April | 32.5 °F | 55.9 °F | 3.44 in. |
| May | 43.6 °F | 67.8 °F | 3.78 in. |
| June | 52.8 °F | 76.5 °F | 4.33 in. |
| July | 58.2 °F | 81.6 °F | 4.34 in. |
| August | 56.0 °F | 80.0 °F | 4.27 in. |
| September | 48.2 °F | 72.8 °F | 4.04 in. |
| October | 37.1 °F | 59.9 °F | 4.84 in. |
| November | 27.9 °F | 47.3 °F | 3.49 in. |
| December | 18.7 °F | 36.0 °F | 4.02 in. |
| Annual | 35 °F | 57.1 °F | 45.96 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 21 - May 31 |
| 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 |