Chillicothe, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6 °C (low) to 17.8 °C (high). Annual precipitation averages 1055.1 Millimeters. Chillicothe is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.6 °C | 3.8 °C | 76.96 mm |
| February | -4.6 °C | 5.6 °C | 72.64 mm |
| March | -0.5 °C | 11.2 °C | 93.73 mm |
| April | 5.2 °C | 18.4 °C | 101.09 mm |
| May | 11.2 °C | 23.7 °C | 111.76 mm |
| June | 15.9 °C | 28.2 °C | 110.24 mm |
| July | 17.8 °C | 29.7 °C | 99.82 mm |
| August | 16.6 °C | 29.3 °C | 82.55 mm |
| September | 12.4 °C | 26.2 °C | 78.49 mm |
| October | 6.1 °C | 19.4 °C | 73.41 mm |
| November | 0.6 °C | 12.2 °C | 72.39 mm |
| December | -2.7 °C | 6.2 °C | 82.04 mm |
| Annual | 6 °C | 17.8 °C | 1055.12 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 |