Des Plaines, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 41.5 °F (low) to 58.9 °F (high). Annual precipitation averages 38 Inches. 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 | 16.8 °F | 31.5 °F | 2.07 in. |
| February | 19.5 °F | 35.2 °F | 1.93 in. |
| March | 28.7 °F | 45.9 °F | 2.28 in. |
| April | 38.9 °F | 57.8 °F | 3.79 in. |
| May | 49.8 °F | 69.1 °F | 4.63 in. |
| June | 59.9 °F | 79.3 °F | 4.41 in. |
| July | 65.3 °F | 83.6 °F | 3.61 in. |
| August | 63.9 °F | 81.8 °F | 3.99 in. |
| September | 55.9 °F | 75.2 °F | 3.34 in. |
| October | 43.8 °F | 62.5 °F | 3.25 in. |
| November | 32.4 °F | 48.3 °F | 2.52 in. |
| December | 22.7 °F | 36.7 °F | 2.2 in. |
| Annual | 41.5 °F | 58.9 °F | 38.02 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 |