Forestport, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.3 °C (low) to 11.6 °C (high). Annual precipitation averages 1343.7 Millimeters. Forestport is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -13.8 °C | -2.9 °C | 107.95 mm |
| February | -13.3 °C | -1.4 °C | 88.39 mm |
| March | -8.6 °C | 3.2 °C | 94.23 mm |
| April | -1.2 °C | 10.8 °C | 101.6 mm |
| May | 5.4 °C | 18.3 °C | 114.81 mm |
| June | 10.7 °C | 22.7 °C | 120.9 mm |
| July | 13.2 °C | 25 °C | 119.63 mm |
| August | 12.3 °C | 24.3 °C | 110.74 mm |
| September | 8.3 °C | 20.4 °C | 119.13 mm |
| October | 2.4 °C | 13.2 °C | 136.14 mm |
| November | -3.1 °C | 6.2 °C | 111 mm |
| December | -9.1 °C | -0.1 °C | 119.13 mm |
| Annual | 0.3 °C | 11.6 °C | 1343.65 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |