Troy, 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 56.3 °F (high). Annual precipitation averages 49.7 Inches. Troy is located in USDA Plant Hardiness Zone 6a. 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 | 12.5 °F | 30.9 °F | 3.83 in. |
| February | 14.2 °F | 34.0 °F | 3.28 in. |
| March | 21.7 °F | 41.6 °F | 3.8 in. |
| April | 33.0 °F | 55.1 °F | 3.8 in. |
| May | 43.4 °F | 67.2 °F | 3.9 in. |
| June | 53.0 °F | 75.5 °F | 4.69 in. |
| July | 58.3 °F | 80.5 °F | 4.36 in. |
| August | 55.7 °F | 78.7 °F | 4.34 in. |
| September | 48.2 °F | 70.8 °F | 4.38 in. |
| October | 38.3 °F | 58.6 °F | 5.15 in. |
| November | 28.8 °F | 46.9 °F | 3.82 in. |
| December | 19.5 °F | 36.3 °F | 4.3 in. |
| Annual | 35.6 °F | 56.3 °F | 49.65 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 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |