Delevan, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2 °C (low) to 13.3 °C (high). Annual precipitation averages 1173.2 Millimeters. Delevan is located in USDA Plant Hardiness Zone 5b. 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 | -10 °C | -0.8 °C | 91.19 mm |
| February | -9.8 °C | 0.4 °C | 68.33 mm |
| March | -6.1 °C | 5.1 °C | 77.22 mm |
| April | 0.1 °C | 12.6 °C | 91.19 mm |
| May | 6.4 °C | 19.4 °C | 97.28 mm |
| June | 11.4 °C | 23.8 °C | 114.81 mm |
| July | 13.7 °C | 26.1 °C | 112.01 mm |
| August | 12.7 °C | 25.6 °C | 107.19 mm |
| September | 9.2 °C | 21.8 °C | 108.97 mm |
| October | 3.6 °C | 15.1 °C | 106.68 mm |
| November | -1.4 °C | 7.8 °C | 98.55 mm |
| December | -5.9 °C | 2.1 °C | 99.82 mm |
| Annual | 2 °C | 13.3 °C | 1173.24 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 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |