Willoughby, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6 °C (low) to 14.5 °C (high). Annual precipitation averages 1079.8 Millimeters. Willoughby is located in USDA Plant Hardiness Zone 7a. 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 | -6.1 °C | 1.3 °C | 80.01 mm |
| February | -5.8 °C | 2.2 °C | 56.9 mm |
| March | -2.2 °C | 6.4 °C | 72.64 mm |
| April | 4 °C | 13.7 °C | 88.14 mm |
| May | 10.2 °C | 19.7 °C | 94.74 mm |
| June | 15.6 °C | 24.7 °C | 95.25 mm |
| July | 17.9 °C | 26.7 °C | 107.7 mm |
| August | 17.3 °C | 25.9 °C | 99.82 mm |
| September | 13.6 °C | 22.7 °C | 105.66 mm |
| October | 7.8 °C | 16.3 °C | 106.17 mm |
| November | 2.3 °C | 9.9 °C | 87.63 mm |
| December | -2.6 °C | 4.1 °C | 85.09 mm |
| Annual | 6 °C | 14.5 °C | 1079.75 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 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |