Wellsville, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.3 °C (low) to 13.7 °C (high). Annual precipitation averages 1011.7 Millimeters. Wellsville is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.9 °C | -0.3 °C | 69.34 mm |
| February | -9.8 °C | 1.1 °C | 46.99 mm |
| March | -6.4 °C | 5.8 °C | 64.26 mm |
| April | -0.6 °C | 13.1 °C | 92.71 mm |
| May | 5.3 °C | 20.1 °C | 92.46 mm |
| June | 10.3 °C | 24.4 °C | 104.65 mm |
| July | 12.7 °C | 26.6 °C | 105.16 mm |
| August | 12 °C | 25.6 °C | 98.3 mm |
| September | 8.2 °C | 22.1 °C | 93.98 mm |
| October | 2.6 °C | 15 °C | 100.33 mm |
| November | -2.3 °C | 8.2 °C | 69.09 mm |
| December | -6.5 °C | 2.3 °C | 74.42 mm |
| Annual | 1.3 °C | 13.7 °C | 1011.69 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 21 - May 31 |
| 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 |