Defiance, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.7 °C (low) to 15.6 °C (high). Annual precipitation averages 929.9 Millimeters. Defiance is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8 °C | 0.3 °C | 62.74 mm |
| February | -7.1 °C | 2.2 °C | 53.85 mm |
| March | -2.4 °C | 8.1 °C | 63.5 mm |
| April | 3.2 °C | 15.6 °C | 88.9 mm |
| May | 9.7 °C | 21.9 °C | 104.14 mm |
| June | 15.3 °C | 27.1 °C | 92.71 mm |
| July | 17.1 °C | 29.2 °C | 92.71 mm |
| August | 15.8 °C | 27.9 °C | 89.41 mm |
| September | 11.6 °C | 24.8 °C | 76.45 mm |
| October | 5.5 °C | 17.6 °C | 70.1 mm |
| November | 0 °C | 9.7 °C | 73.66 mm |
| December | -4.7 °C | 3.1 °C | 61.72 mm |
| Annual | 4.7 °C | 15.6 °C | 929.89 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |