Hannibal, Ohio has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 5.5 °C (low) to 17.7 °C (high). Annual precipitation averages 1182.9 Millimeters. Hannibal is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.8 °C | 4.1 °C | 94.74 mm |
| February | -4.9 °C | 5.9 °C | 78.74 mm |
| March | -1.3 °C | 11.2 °C | 103.38 mm |
| April | 4.2 °C | 18.8 °C | 100.08 mm |
| May | 9.9 °C | 23.4 °C | 116.84 mm |
| June | 14.9 °C | 27.6 °C | 119.63 mm |
| July | 17.3 °C | 29.3 °C | 120.14 mm |
| August | 16.6 °C | 28.9 °C | 95.25 mm |
| September | 12.6 °C | 25.7 °C | 97.54 mm |
| October | 5.9 °C | 19.3 °C | 81.28 mm |
| November | 0.3 °C | 12.3 °C | 82.8 mm |
| December | -3.2 °C | 6.3 °C | 92.46 mm |
| Annual | 5.5 °C | 17.7 °C | 1182.88 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |