Des Plaines, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.3 °C (low) to 15 °C (high). Annual precipitation averages 965.7 Millimeters. Des Plaines 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 | -8.4 °C | -0.3 °C | 52.58 mm |
| February | -6.9 °C | 1.8 °C | 49.02 mm |
| March | -1.8 °C | 7.7 °C | 57.91 mm |
| April | 3.8 °C | 14.3 °C | 96.27 mm |
| May | 9.9 °C | 20.6 °C | 117.6 mm |
| June | 15.5 °C | 26.3 °C | 112.01 mm |
| July | 18.5 °C | 28.7 °C | 91.69 mm |
| August | 17.7 °C | 27.7 °C | 101.35 mm |
| September | 13.3 °C | 24 °C | 84.84 mm |
| October | 6.6 °C | 16.9 °C | 82.55 mm |
| November | 0.2 °C | 9.1 °C | 64.01 mm |
| December | -5.2 °C | 2.6 °C | 55.88 mm |
| Annual | 5.3 °C | 15 °C | 965.71 mm |
| 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 : -23.3°C to -20.6°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 |