Mounds, Illinois has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.9 °C (low) to 20.1 °C (high). Annual precipitation averages 1272.6 Millimeters. Mounds is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.9 °C | 6.3 °C | 97.54 mm |
| February | -1.3 °C | 9.1 °C | 96.01 mm |
| March | 3.1 °C | 14.4 °C | 122.43 mm |
| April | 8.7 °C | 20.7 °C | 135.64 mm |
| May | 14.3 °C | 25.7 °C | 133.35 mm |
| June | 19 °C | 30.2 °C | 109.73 mm |
| July | 20.9 °C | 31.7 °C | 97.79 mm |
| August | 19.4 °C | 30.9 °C | 73.66 mm |
| September | 14.9 °C | 27.8 °C | 87.12 mm |
| October | 8.4 °C | 21.9 °C | 99.57 mm |
| November | 2.9 °C | 14.3 °C | 111.76 mm |
| December | -1 °C | 8.2 °C | 107.95 mm |
| Annual | 8.9 °C | 20.1 °C | 1272.55 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |