Hannibal, New York has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.8 °C (low) to 13.6 °C (high). Annual precipitation averages 1141.2 Millimeters. Hannibal is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.9 °C | -0.3 °C | 99.82 mm |
| February | -8.3 °C | 0.6 °C | 78.23 mm |
| March | -4.4 °C | 5.1 °C | 82.3 mm |
| April | 1.7 °C | 12.4 °C | 91.19 mm |
| May | 8 °C | 19.7 °C | 88.65 mm |
| June | 13.1 °C | 24.2 °C | 91.69 mm |
| July | 16 °C | 26.7 °C | 92.46 mm |
| August | 15.3 °C | 26.2 °C | 94.23 mm |
| September | 11.6 °C | 22.4 °C | 95.25 mm |
| October | 5.8 °C | 15.1 °C | 118.87 mm |
| November | 0.6 °C | 8.8 °C | 103.12 mm |
| December | -4.7 °C | 2.7 °C | 105.41 mm |
| Annual | 3.8 °C | 13.6 °C | 1141.22 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |