Mill Shoals, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 45.6 °F (low) to 66.3 °F (high). Annual precipitation averages 45.9 Inches. 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 | 23.9 °F | 40.0 °F | 3.39 in. |
| February | 26.5 °F | 45.1 °F | 2.79 in. |
| March | 34.7 °F | 55.1 °F | 4.01 in. |
| April | 45.1 °F | 67.1 °F | 4.93 in. |
| May | 55.7 °F | 76.4 °F | 4.99 in. |
| June | 64.2 °F | 85.1 °F | 4.65 in. |
| July | 67.1 °F | 87.9 °F | 4.02 in. |
| August | 64.6 °F | 87.0 °F | 3.24 in. |
| September | 57.1 °F | 81.4 °F | 3.16 in. |
| October | 45.5 °F | 69.9 °F | 3.46 in. |
| November | 35.3 °F | 55.6 °F | 3.95 in. |
| December | 27.8 °F | 44.4 °F | 3.35 in. |
| Annual | 45.6 °F | 66.3 °F | 45.94 in. |
| 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 : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |