Port Henry, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 36.3 °F (low) to 56.3 °F (high). Annual precipitation averages 37.9 Inches. Port Henry is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 10.9 °F | 29.2 °F | 2.5 in. |
| February | 11.8 °F | 31.3 °F | 2.07 in. |
| March | 21.8 °F | 40.1 °F | 2.88 in. |
| April | 33.5 °F | 55.3 °F | 3.1 in. |
| May | 45.4 °F | 68.0 °F | 3.1 in. |
| June | 55.1 °F | 76.8 °F | 4.17 in. |
| July | 60.0 °F | 82.1 °F | 4.03 in. |
| August | 58.4 °F | 80.3 °F | 3.6 in. |
| September | 50.4 °F | 72.9 °F | 3.19 in. |
| October | 39.1 °F | 58.9 °F | 3.6 in. |
| November | 29.9 °F | 46.0 °F | 2.72 in. |
| December | 19.0 °F | 34.5 °F | 2.92 in. |
| Annual | 36.3 °F | 56.3 °F | 37.88 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5a : -20°F to -15°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 |