Mundelein, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40 °F (low) to 58.1 °F (high). Annual precipitation averages 38 Inches. 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 | 15.2 °F | 30.3 °F | 1.93 in. |
| February | 17.9 °F | 34.0 °F | 1.97 in. |
| March | 27.2 °F | 44.9 °F | 2.33 in. |
| April | 37.5 °F | 57.3 °F | 3.87 in. |
| May | 48.1 °F | 68.5 °F | 4.5 in. |
| June | 58.2 °F | 78.6 °F | 4.49 in. |
| July | 63.6 °F | 83.0 °F | 3.82 in. |
| August | 62.3 °F | 81.2 °F | 3.79 in. |
| September | 54.4 °F | 74.4 °F | 3.47 in. |
| October | 42.7 °F | 61.7 °F | 3.24 in. |
| November | 31.3 °F | 47.5 °F | 2.43 in. |
| December | 21.3 °F | 35.7 °F | 2.11 in. |
| Annual | 40 °F | 58.1 °F | 37.95 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 5b : -15°F to -10°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 |