Port Gibson, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 4.4 °C (low) to 14.3 °C (high). Annual precipitation averages 929.1 Millimeters. Port Gibson is located in USDA Plant Hardiness Zone 6b. 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 | -7.9 °C | 0.3 °C | 67.56 mm |
| February | -7.2 °C | 1.2 °C | 53.34 mm |
| March | -3.6 °C | 5.7 °C | 67.06 mm |
| April | 2.3 °C | 13.2 °C | 73.66 mm |
| May | 8.6 °C | 20.3 °C | 81.28 mm |
| June | 14 °C | 25.1 °C | 87.88 mm |
| July | 16.4 °C | 27.6 °C | 91.44 mm |
| August | 15.6 °C | 26.8 °C | 89.66 mm |
| September | 11.7 °C | 22.7 °C | 81.79 mm |
| October | 6 °C | 15.9 °C | 91.95 mm |
| November | 0.6 °C | 9.1 °C | 73.15 mm |
| December | -4.2 °C | 3.1 °C | 70.36 mm |
| Annual | 4.4 °C | 14.3 °C | 929.13 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 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |