Gurnee, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.8 °C (low) to 13.9 °C (high). Annual precipitation averages 940.1 Millimeters. Gurnee 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 | -8.9 °C | -0.8 °C | 53.09 mm |
| February | -7.4 °C | 1.1 °C | 52.58 mm |
| March | -2.3 °C | 6.6 °C | 56.9 mm |
| April | 3.2 °C | 12.7 °C | 94.49 mm |
| May | 9.1 °C | 19 °C | 109.98 mm |
| June | 14.8 °C | 24.6 °C | 108.46 mm |
| July | 17.9 °C | 27.3 °C | 88.39 mm |
| August | 17.4 °C | 26.6 °C | 89.92 mm |
| September | 13 °C | 22.9 °C | 87.63 mm |
| October | 6.4 °C | 16.1 °C | 80.52 mm |
| November | 0.1 °C | 8.6 °C | 62.99 mm |
| December | -5.4 °C | 2.1 °C | 55.12 mm |
| Annual | 4.8 °C | 13.9 °C | 940.07 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 | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |