Marengo, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 43.3 °F (low) to 66.1 °F (high). Annual precipitation averages 52.8 Inches. 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 | 22.1 °F | 41.2 °F | 3.83 in. |
| February | 24.8 °F | 46.0 °F | 3.6 in. |
| March | 32.4 °F | 55.6 °F | 4.81 in. |
| April | 41.9 °F | 67.4 °F | 5.6 in. |
| May | 52.5 °F | 76.0 °F | 5.61 in. |
| June | 60.9 °F | 83.5 °F | 5.23 in. |
| July | 64.4 °F | 86.5 °F | 4.68 in. |
| August | 62.6 °F | 86.0 °F | 3.51 in. |
| September | 55.0 °F | 80.4 °F | 3.77 in. |
| October | 43.2 °F | 69.2 °F | 3.88 in. |
| November | 33.6 °F | 56.0 °F | 4.01 in. |
| December | 26.7 °F | 45.1 °F | 4.27 in. |
| Annual | 43.3 °F | 66.1 °F | 52.8 in. |
| 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 : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |