Mill Shoals, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.6 °C (low) to 19 °C (high). Annual precipitation averages 1166.9 Millimeters. Mill Shoals is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.5 °C | 4.4 °C | 86.11 mm |
| February | -3.1 °C | 7.3 °C | 70.87 mm |
| March | 1.5 °C | 12.8 °C | 101.85 mm |
| April | 7.3 °C | 19.5 °C | 125.22 mm |
| May | 13.2 °C | 24.7 °C | 126.75 mm |
| June | 17.9 °C | 29.5 °C | 118.11 mm |
| July | 19.5 °C | 31.1 °C | 102.11 mm |
| August | 18.1 °C | 30.6 °C | 82.3 mm |
| September | 13.9 °C | 27.4 °C | 80.26 mm |
| October | 7.5 °C | 21.1 °C | 87.88 mm |
| November | 1.8 °C | 13.1 °C | 100.33 mm |
| December | -2.3 °C | 6.9 °C | 85.09 mm |
| Annual | 7.6 °C | 19 °C | 1166.88 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |