Wilmette, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 43.7 °F (low) to 58.5 °F (high). Annual precipitation averages 39.4 Inches. 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 | 19.1 °F | 32.0 °F | 2.24 in. |
| February | 22.0 °F | 35.8 °F | 2.15 in. |
| March | 30.5 °F | 45.4 °F | 2.21 in. |
| April | 40.3 °F | 56.9 °F | 3.84 in. |
| May | 50.5 °F | 67.9 °F | 4.59 in. |
| June | 60.7 °F | 77.8 °F | 4.38 in. |
| July | 67.4 °F | 82.4 °F | 3.78 in. |
| August | 67.0 °F | 80.9 °F | 4.12 in. |
| September | 59.6 °F | 74.5 °F | 3.57 in. |
| October | 47.0 °F | 62.6 °F | 3.53 in. |
| November | 35.3 °F | 48.6 °F | 2.65 in. |
| December | 25.1 °F | 37.3 °F | 2.33 in. |
| Annual | 43.7 °F | 58.5 °F | 39.39 in. |
| 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 : -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 |