Brookport, Illinois has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 47.9 °F (low) to 68.1 °F (high). Annual precipitation averages 50.2 Inches. Brookport is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 26.5 °F | 43.3 °F | 3.96 in. |
| February | 29.5 °F | 47.9 °F | 3.55 in. |
| March | 37.5 °F | 58.0 °F | 4.7 in. |
| April | 47.1 °F | 69.4 °F | 5.2 in. |
| May | 57.3 °F | 77.6 °F | 5.18 in. |
| June | 65.6 °F | 85.8 °F | 4.62 in. |
| July | 69.5 °F | 89.1 °F | 4.05 in. |
| August | 67.3 °F | 88.1 °F | 2.94 in. |
| September | 59.5 °F | 82.1 °F | 3.51 in. |
| October | 47.9 °F | 71.0 °F | 3.82 in. |
| November | 37.3 °F | 57.7 °F | 4.2 in. |
| December | 30.1 °F | 46.9 °F | 4.48 in. |
| Annual | 47.9 °F | 68.1 °F | 50.21 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 7a : 0°F to 5°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |