New Philadelphia, Ohio has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 4.8 °C (low) to 16.4 °C (high). Annual precipitation averages 1074.7 Millimeters. New Philadelphia 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 | -6.9 °C | 2.2 °C | 78.74 mm |
| February | -6.2 °C | 3.9 °C | 59.69 mm |
| March | -2 °C | 9.3 °C | 85.09 mm |
| April | 3.6 °C | 16.9 °C | 96.27 mm |
| May | 9.5 °C | 22.5 °C | 106.17 mm |
| June | 14.4 °C | 26.9 °C | 127 mm |
| July | 16.6 °C | 28.8 °C | 107.7 mm |
| August | 15.5 °C | 28.2 °C | 96.77 mm |
| September | 11.4 °C | 24.8 °C | 84.07 mm |
| October | 5.2 °C | 18 °C | 82.55 mm |
| November | 0.1 °C | 10.9 °C | 74.68 mm |
| December | -3.8 °C | 4.8 °C | 75.95 mm |
| Annual | 4.8 °C | 16.4 °C | 1074.68 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 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 |