Petersburg, Ohio has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 4 °C (low) to 15.7 °C (high). Annual precipitation averages 1046.5 Millimeters. Petersburg is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.7 °C | 1.6 °C | 76.45 mm |
| February | -7.3 °C | 3.3 °C | 58.93 mm |
| March | -3 °C | 8.5 °C | 78.99 mm |
| April | 2.8 °C | 15.8 °C | 95.5 mm |
| May | 8.3 °C | 21.6 °C | 98.04 mm |
| June | 13.3 °C | 26.2 °C | 110.74 mm |
| July | 15.5 °C | 28.3 °C | 111.25 mm |
| August | 14.6 °C | 27.6 °C | 89.92 mm |
| September | 10.8 °C | 24.2 °C | 95.76 mm |
| October | 4.8 °C | 17.2 °C | 80.52 mm |
| November | -0.1 °C | 10.2 °C | 73.91 mm |
| December | -4.3 °C | 4.3 °C | 76.45 mm |
| Annual | 4 °C | 15.7 °C | 1046.46 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 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 | Dfb - Humid Continental Mild Summer, Wet All Year |