Johnstown, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5 °C (low) to 15.9 °C (high). Annual precipitation averages 1067.1 Millimeters. Johnstown is located in USDA Plant Hardiness Zone 6a. 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 | -7.3 °C | 1.4 °C | 76.45 mm |
| February | -6.2 °C | 3.3 °C | 58.93 mm |
| March | -1.7 °C | 9.1 °C | 84.84 mm |
| April | 4.2 °C | 16.4 °C | 100.08 mm |
| May | 10.1 °C | 21.9 °C | 108.71 mm |
| June | 15.2 °C | 26.6 °C | 115.57 mm |
| July | 16.9 °C | 28.3 °C | 115.06 mm |
| August | 15.9 °C | 27.5 °C | 93.22 mm |
| September | 11.9 °C | 24.3 °C | 88.65 mm |
| October | 5.4 °C | 17.5 °C | 72.14 mm |
| November | 0 °C | 10.2 °C | 76.45 mm |
| December | -4.2 °C | 4 °C | 76.96 mm |
| Annual | 5 °C | 15.9 °C | 1067.06 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 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |