Wilmette, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.5 °C (low) to 14.7 °C (high). Annual precipitation averages 1000.5 Millimeters. Wilmette 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 | -7.2 °C | 0 °C | 56.9 mm |
| February | -5.6 °C | 2.1 °C | 54.61 mm |
| March | -0.8 °C | 7.4 °C | 56.13 mm |
| April | 4.6 °C | 13.8 °C | 97.54 mm |
| May | 10.3 °C | 19.9 °C | 116.59 mm |
| June | 15.9 °C | 25.4 °C | 111.25 mm |
| July | 19.7 °C | 28 °C | 96.01 mm |
| August | 19.4 °C | 27.2 °C | 104.65 mm |
| September | 15.3 °C | 23.6 °C | 90.68 mm |
| October | 8.3 °C | 17 °C | 89.66 mm |
| November | 1.8 °C | 9.2 °C | 67.31 mm |
| December | -3.8 °C | 2.9 °C | 59.18 mm |
| Annual | 6.5 °C | 14.7 °C | 1000.51 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 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |