Marengo, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.7 °C (low) to 15.6 °C (high). Annual precipitation averages 1066.3 Millimeters. Marengo 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 | -7.7 °C | 1.1 °C | 80.77 mm |
| February | -6.7 °C | 2.7 °C | 59.94 mm |
| March | -2.2 °C | 8.4 °C | 81.28 mm |
| April | 3.7 °C | 16.1 °C | 101.6 mm |
| May | 9.8 °C | 21.9 °C | 110.74 mm |
| June | 14.9 °C | 26.4 °C | 118.36 mm |
| July | 16.7 °C | 28.3 °C | 109.73 mm |
| August | 15.6 °C | 27.5 °C | 91.19 mm |
| September | 11.6 °C | 24.2 °C | 85.6 mm |
| October | 5.3 °C | 17.4 °C | 72.9 mm |
| November | -0.1 °C | 9.9 °C | 77.22 mm |
| December | -4.4 °C | 3.7 °C | 76.96 mm |
| Annual | 4.7 °C | 15.6 °C | 1066.29 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 |