Mundelein, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.4 °C (low) to 14.5 °C (high). Annual precipitation averages 963.9 Millimeters. Mundelein is located in USDA Plant Hardiness Zone 5b. 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 | -9.3 °C | -0.9 °C | 49.02 mm |
| February | -7.8 °C | 1.1 °C | 50.04 mm |
| March | -2.7 °C | 7.2 °C | 59.18 mm |
| April | 3.1 °C | 14.1 °C | 98.3 mm |
| May | 8.9 °C | 20.3 °C | 114.3 mm |
| June | 14.6 °C | 25.9 °C | 114.05 mm |
| July | 17.6 °C | 28.3 °C | 97.03 mm |
| August | 16.8 °C | 27.3 °C | 96.27 mm |
| September | 12.4 °C | 23.6 °C | 88.14 mm |
| October | 5.9 °C | 16.5 °C | 82.3 mm |
| November | -0.4 °C | 8.6 °C | 61.72 mm |
| December | -5.9 °C | 2.1 °C | 53.59 mm |
| Annual | 4.4 °C | 14.5 °C | 963.94 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 5b : -26.1°C to -23.3°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 |