West Chicago, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.2 °C (low) to 15.2 °C (high). Annual precipitation averages 986.3 Millimeters. West Chicago 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.5 °C | -0.7 °C | 51.82 mm |
| February | -8 °C | 1.5 °C | 49.78 mm |
| March | -2.7 °C | 8.1 °C | 59.44 mm |
| April | 3.1 °C | 15.2 °C | 97.03 mm |
| May | 9.2 °C | 21.5 °C | 124.21 mm |
| June | 14.7 °C | 26.9 °C | 112.01 mm |
| July | 17.3 °C | 29.2 °C | 95.5 mm |
| August | 16.4 °C | 27.9 °C | 101.85 mm |
| September | 12 °C | 24.4 °C | 84.84 mm |
| October | 5.3 °C | 17.1 °C | 88.39 mm |
| November | -0.8 °C | 9 °C | 65.53 mm |
| December | -6.2 °C | 2.2 °C | 55.88 mm |
| Annual | 4.2 °C | 15.2 °C | 986.28 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |