Glenwillow, Ohio has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 5 °C (low) to 15.2 °C (high). Annual precipitation averages 1082.3 Millimeters. Glenwillow 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 | -7.1 °C | 1.1 °C | 77.22 mm |
| February | -6.7 °C | 2.4 °C | 59.69 mm |
| March | -2.6 °C | 7.3 °C | 83.57 mm |
| April | 3.7 °C | 14.7 °C | 98.81 mm |
| May | 9.6 °C | 21.3 °C | 104.9 mm |
| June | 14.7 °C | 25.9 °C | 106.68 mm |
| July | 16.8 °C | 28.2 °C | 106.17 mm |
| August | 15.9 °C | 27.3 °C | 95.5 mm |
| September | 12.1 °C | 23.6 °C | 99.06 mm |
| October | 6.2 °C | 16.7 °C | 90.17 mm |
| November | 1.1 °C | 9.7 °C | 80.77 mm |
| December | -3.6 °C | 3.7 °C | 79.76 mm |
| Annual | 5 °C | 15.2 °C | 1082.3 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 |