Roswell, Ohio has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 5 °C (low) to 16.3 °C (high). Annual precipitation averages 1076.7 Millimeters. Roswell 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.8 °C | 2.1 °C | 78.23 mm |
| February | -6.2 °C | 3.8 °C | 58.42 mm |
| March | -1.9 °C | 9.3 °C | 84.07 mm |
| April | 3.8 °C | 16.7 °C | 97.03 mm |
| May | 9.7 °C | 22.3 °C | 106.17 mm |
| June | 14.6 °C | 26.8 °C | 129.79 mm |
| July | 16.7 °C | 28.7 °C | 106.17 mm |
| August | 15.7 °C | 28.1 °C | 96.52 mm |
| September | 11.7 °C | 24.6 °C | 86.61 mm |
| October | 5.5 °C | 17.9 °C | 82.55 mm |
| November | 0.3 °C | 10.8 °C | 74.42 mm |
| December | -3.7 °C | 4.7 °C | 76.71 mm |
| Annual | 5 °C | 16.3 °C | 1076.69 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 |