Chicago, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.2 °C (low) to 14.9 °C (high). Annual precipitation averages 1025.1 Millimeters. Chicago is located in USDA Plant Hardiness Zone 6b. 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 | -6.4 °C | 0.6 °C | 60.45 mm |
| February | -5 °C | 2.7 °C | 55.88 mm |
| March | -0.1 °C | 7.9 °C | 57.66 mm |
| April | 5.4 °C | 14.1 °C | 100.84 mm |
| May | 11.2 °C | 19.9 °C | 117.86 mm |
| June | 16.9 °C | 25.2 °C | 113.28 mm |
| July | 20.4 °C | 27.4 °C | 103.63 mm |
| August | 19.8 °C | 27.1 °C | 102.87 mm |
| September | 15.7 °C | 23.5 °C | 84.07 mm |
| October | 8.8 °C | 16.9 °C | 95.76 mm |
| November | 2.4 °C | 9.7 °C | 70.1 mm |
| December | -3.3 °C | 3.2 °C | 62.74 mm |
| Annual | 7.2 °C | 14.9 °C | 1025.14 mm |
| 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 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |