Marengo, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.3 °C (low) to 18.9 °C (high). Annual precipitation averages 1341.1 Millimeters. Marengo is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.5 °C | 5.1 °C | 97.28 mm |
| February | -4 °C | 7.8 °C | 91.44 mm |
| March | 0.2 °C | 13.1 °C | 122.17 mm |
| April | 5.5 °C | 19.7 °C | 142.24 mm |
| May | 11.4 °C | 24.4 °C | 142.49 mm |
| June | 16.1 °C | 28.6 °C | 132.84 mm |
| July | 18 °C | 30.3 °C | 118.87 mm |
| August | 17 °C | 30 °C | 89.15 mm |
| September | 12.8 °C | 26.9 °C | 95.76 mm |
| October | 6.2 °C | 20.7 °C | 98.55 mm |
| November | 0.9 °C | 13.3 °C | 101.85 mm |
| December | -2.9 °C | 7.3 °C | 108.46 mm |
| Annual | 6.3 °C | 18.9 °C | 1341.1 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 | Dfa - Humid Continental Hot Summers With Year Around Precipitation |