Hornell, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2 °C (low) to 14.1 °C (high). Annual precipitation averages 933.5 Millimeters. Hornell 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 Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.7 °C | 0.1 °C | 57.66 mm |
| February | -9.4 °C | 1.4 °C | 47.5 mm |
| March | -5.7 °C | 5.8 °C | 63.5 mm |
| April | 0.2 °C | 13.3 °C | 80.01 mm |
| May | 6.1 °C | 20.3 °C | 85.09 mm |
| June | 11.2 °C | 24.9 °C | 99.82 mm |
| July | 13.5 °C | 27.3 °C | 93.22 mm |
| August | 12.7 °C | 26.4 °C | 95 mm |
| September | 9 °C | 22.7 °C | 92.46 mm |
| October | 3.4 °C | 15.4 °C | 90.93 mm |
| November | -1.6 °C | 8.6 °C | 66.55 mm |
| December | -6.1 °C | 2.8 °C | 61.72 mm |
| Annual | 2 °C | 14.1 °C | 933.46 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| 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 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |