Fort Johnson, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.6 °C (low) to 14.3 °C (high). Annual precipitation averages 1076.2 Millimeters. Fort Johnson is located in USDA Plant Hardiness Zone 5b. 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 | -9.7 °C | -0.5 °C | 80.26 mm |
| February | -8.9 °C | 1.1 °C | 63.5 mm |
| March | -4.4 °C | 5.8 °C | 83.57 mm |
| April | 2.2 °C | 13.9 °C | 87.38 mm |
| May | 8.7 °C | 20.8 °C | 88.14 mm |
| June | 13.5 °C | 25.3 °C | 115.82 mm |
| July | 16.4 °C | 27.8 °C | 108.97 mm |
| August | 15.4 °C | 27.1 °C | 98.04 mm |
| September | 11.3 °C | 23.1 °C | 88.39 mm |
| October | 5 °C | 16.3 °C | 98.04 mm |
| November | -0.7 °C | 8.6 °C | 83.06 mm |
| December | -5.6 °C | 2.4 °C | 81.03 mm |
| Annual | 3.6 °C | 14.3 °C | 1076.2 mm |
| 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 5b : -26.1°C to -23.3°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 |