Merrionette Park, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 42.6 °F (low) to 59.9 °F (high). Annual precipitation averages 39.7 Inches. Merrionette Park is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 17.9 °F | 32.2 °F | 2.17 in. |
| February | 20.6 °F | 35.9 °F | 2.08 in. |
| March | 29.9 °F | 46.7 °F | 2.38 in. |
| April | 40.2 °F | 59.3 °F | 3.92 in. |
| May | 51.1 °F | 70.3 °F | 4.62 in. |
| June | 61.2 °F | 80.2 °F | 4.32 in. |
| July | 66.4 °F | 84.6 °F | 4.39 in. |
| August | 64.6 °F | 82.7 °F | 4.17 in. |
| September | 57.3 °F | 76.4 °F | 3.24 in. |
| October | 44.9 °F | 63.5 °F | 3.49 in. |
| November | 33.9 °F | 49.4 °F | 2.63 in. |
| December | 23.6 °F | 37.4 °F | 2.32 in. |
| Annual | 42.6 °F | 59.9 °F | 39.73 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°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 |