Hannibal, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.7 °C (low) to 17.7 °C (high). Annual precipitation averages 1004.3 Millimeters. Hannibal is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7 °C | 2.2 °C | 48.77 mm |
| February | -5.1 °C | 5.2 °C | 54.86 mm |
| March | 0.1 °C | 11.3 °C | 70.61 mm |
| April | 6.2 °C | 18.1 °C | 107.95 mm |
| May | 12.1 °C | 23.7 °C | 124.46 mm |
| June | 17.5 °C | 28.7 °C | 113.79 mm |
| July | 19.5 °C | 30.8 °C | 99.31 mm |
| August | 18.4 °C | 30.2 °C | 93.73 mm |
| September | 13.8 °C | 26.3 °C | 87.12 mm |
| October | 7.6 °C | 19.4 °C | 81.53 mm |
| November | 1.2 °C | 11.7 °C | 69.34 mm |
| December | -4.2 °C | 5 °C | 52.83 mm |
| Annual | 6.7 °C | 17.7 °C | 1004.3 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 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 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |