Smithville, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.8 °C (low) to 15.3 °C (high). Annual precipitation averages 1018 Millimeters. Smithville is located in USDA Plant Hardiness Zone 6a. 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 | -7.4 °C | 1 °C | 69.6 mm |
| February | -6.7 °C | 2.7 °C | 53.09 mm |
| March | -2.3 °C | 8 °C | 75.95 mm |
| April | 3.7 °C | 15.5 °C | 96.77 mm |
| May | 9.6 °C | 21.3 °C | 103.12 mm |
| June | 14.7 °C | 26.1 °C | 110.74 mm |
| July | 16.6 °C | 27.8 °C | 100.33 mm |
| August | 15.6 °C | 27.1 °C | 94.49 mm |
| September | 11.6 °C | 23.8 °C | 87.12 mm |
| October | 5.6 °C | 16.9 °C | 83.31 mm |
| November | 0.3 °C | 9.9 °C | 73.41 mm |
| December | -4.1 °C | 3.7 °C | 70.1 mm |
| Annual | 4.8 °C | 15.3 °C | 1018.03 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 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 | Dfa - Humid Continental Hot Summers With Year Around Precipitation |