Hillside, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41.6 °F (low) to 59.6 °F (high). Annual precipitation averages 39.5 Inches. Hillside 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 | 16.9 °F | 31.7 °F | 2.16 in. |
| February | 19.6 °F | 35.5 °F | 2.15 in. |
| March | 28.9 °F | 46.5 °F | 2.34 in. |
| April | 39.2 °F | 59.0 °F | 3.95 in. |
| May | 50.1 °F | 70.2 °F | 4.72 in. |
| June | 60.2 °F | 80.3 °F | 4.42 in. |
| July | 65.4 °F | 84.6 °F | 3.88 in. |
| August | 63.9 °F | 82.6 °F | 4.16 in. |
| September | 55.9 °F | 76.0 °F | 3.36 in. |
| October | 43.7 °F | 63.0 °F | 3.47 in. |
| November | 32.4 °F | 48.8 °F | 2.58 in. |
| December | 22.7 °F | 36.9 °F | 2.29 in. |
| Annual | 41.6 °F | 59.6 °F | 39.48 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 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |