Highland Park, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 42.7 °F (low) to 58.2 °F (high). Annual precipitation averages 38.7 Inches. Highland Park is located in USDA Plant Hardiness Zone 6a. 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 | 18.2 °F | 31.4 °F | 2.1 in. |
| February | 20.9 °F | 35.1 °F | 2.0 in. |
| March | 29.6 °F | 44.8 °F | 2.21 in. |
| April | 39.5 °F | 56.0 °F | 3.84 in. |
| May | 49.8 °F | 67.7 °F | 4.62 in. |
| June | 60.0 °F | 77.9 °F | 4.26 in. |
| July | 66.4 °F | 82.7 °F | 3.74 in. |
| August | 65.9 °F | 81.1 °F | 4.04 in. |
| September | 58.0 °F | 74.5 °F | 3.59 in. |
| October | 46.0 °F | 62.0 °F | 3.46 in. |
| November | 34.4 °F | 48.0 °F | 2.61 in. |
| December | 24.2 °F | 36.7 °F | 2.21 in. |
| Annual | 42.7 °F | 58.2 °F | 38.68 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°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 |