Grandwood Park, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39.4 °F (low) to 57.3 °F (high). Annual precipitation averages 37.8 Inches. Grandwood Park is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 14.6 °F | 29.6 °F | 1.99 in. |
| February | 17.3 °F | 33.2 °F | 2.0 in. |
| March | 26.6 °F | 43.9 °F | 2.28 in. |
| April | 36.9 °F | 56.4 °F | 3.92 in. |
| May | 47.6 °F | 67.7 °F | 4.35 in. |
| June | 57.7 °F | 77.6 °F | 4.5 in. |
| July | 62.8 °F | 82.1 °F | 3.71 in. |
| August | 61.5 °F | 80.5 °F | 3.63 in. |
| September | 53.7 °F | 73.7 °F | 3.57 in. |
| October | 42.1 °F | 60.9 °F | 3.21 in. |
| November | 31.0 °F | 47.1 °F | 2.44 in. |
| December | 20.8 °F | 35.0 °F | 2.19 in. |
| Annual | 39.4 °F | 57.3 °F | 37.79 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |