Oak Lawn, 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. Oak Lawn is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 17.9 °F | 32.0 °F | 2.16 in. |
| February | 20.7 °F | 35.7 °F | 2.05 in. |
| March | 30.0 °F | 46.5 °F | 2.38 in. |
| April | 40.3 °F | 59.5 °F | 3.95 in. |
| May | 51.2 °F | 70.6 °F | 4.73 in. |
| June | 61.4 °F | 80.6 °F | 4.31 in. |
| July | 66.3 °F | 85.0 °F | 4.36 in. |
| August | 64.7 °F | 82.9 °F | 4.18 in. |
| September | 57.1 °F | 76.6 °F | 3.21 in. |
| October | 44.8 °F | 63.5 °F | 3.44 in. |
| November | 33.7 °F | 49.1 °F | 2.55 in. |
| December | 23.6 °F | 37.3 °F | 2.34 in. |
| Annual | 42.6 °F | 59.9 °F | 39.66 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| 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 | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |