Halfmoon, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.8 °C (low) to 14.6 °C (high). Annual precipitation averages 1086.9 Millimeters. Halfmoon is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.3 °C | -0.1 °C | 75.18 mm |
| February | -8.6 °C | 1.5 °C | 55.63 mm |
| March | -3.9 °C | 6.5 °C | 75.44 mm |
| April | 2.4 °C | 14.4 °C | 85.85 mm |
| May | 8.8 °C | 20.9 °C | 90.68 mm |
| June | 13.8 °C | 25.6 °C | 118.36 mm |
| July | 16.2 °C | 28.6 °C | 114.55 mm |
| August | 15.7 °C | 27.1 °C | 107.44 mm |
| September | 11.3 °C | 23.1 °C | 97.03 mm |
| October | 5.1 °C | 16 °C | 104.9 mm |
| November | -0.4 °C | 9.1 °C | 76.96 mm |
| December | -5.3 °C | 2.8 °C | 84.84 mm |
| Annual | 3.8 °C | 14.6 °C | 1086.86 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |