Dellroy, Ohio has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 5.1 °C (low) to 16.4 °C (high). Annual precipitation averages 1068.8 Millimeters. Dellroy is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.7 °C | 2.1 °C | 77.22 mm |
| February | -6 °C | 3.8 °C | 56.64 mm |
| March | -1.8 °C | 9.2 °C | 81.53 mm |
| April | 3.8 °C | 16.8 °C | 94.74 mm |
| May | 9.7 °C | 22.4 °C | 105.41 mm |
| June | 14.6 °C | 26.8 °C | 129.29 mm |
| July | 16.8 °C | 28.8 °C | 108.2 mm |
| August | 15.8 °C | 28.2 °C | 95.76 mm |
| September | 11.9 °C | 24.8 °C | 90.17 mm |
| October | 5.7 °C | 17.9 °C | 81.03 mm |
| November | 0.4 °C | 10.8 °C | 72.9 mm |
| December | -3.6 °C | 4.8 °C | 75.95 mm |
| Annual | 5.1 °C | 16.4 °C | 1068.84 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| 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 | Dfb - Humid Continental Mild Summer, Wet All Year |