Dexter, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.8 °C (low) to 12.9 °C (high). Annual precipitation averages 1046 Millimeters. Dexter is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.6 °C | -1.7 °C | 91.69 mm |
| February | -11.3 °C | -0.8 °C | 69.34 mm |
| March | -5.8 °C | 3.9 °C | 71.88 mm |
| April | 1.2 °C | 11.8 °C | 86.61 mm |
| May | 7.7 °C | 18.8 °C | 77.72 mm |
| June | 13.1 °C | 23.7 °C | 82.8 mm |
| July | 16.2 °C | 26.3 °C | 75.69 mm |
| August | 15.3 °C | 25.7 °C | 82.3 mm |
| September | 11 °C | 21.9 °C | 89.92 mm |
| October | 5.2 °C | 14.7 °C | 120.9 mm |
| November | -0.6 °C | 8.1 °C | 100.84 mm |
| December | -6.5 °C | 1.8 °C | 96.27 mm |
| Annual | 2.8 °C | 12.9 °C | 1045.96 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| 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 |