Brookport, Illinois has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.8 °C (low) to 20 °C (high). Annual precipitation averages 1275.3 Millimeters. 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 | -3.1 °C | 6.3 °C | 100.58 mm |
| February | -1.4 °C | 8.8 °C | 90.17 mm |
| March | 3.1 °C | 14.4 °C | 119.38 mm |
| April | 8.4 °C | 20.8 °C | 132.08 mm |
| May | 14.1 °C | 25.3 °C | 131.57 mm |
| June | 18.7 °C | 29.9 °C | 117.35 mm |
| July | 20.8 °C | 31.7 °C | 102.87 mm |
| August | 19.6 °C | 31.2 °C | 74.68 mm |
| September | 15.3 °C | 27.8 °C | 89.15 mm |
| October | 8.8 °C | 21.7 °C | 97.03 mm |
| November | 2.9 °C | 14.3 °C | 106.68 mm |
| December | -1.1 °C | 8.3 °C | 113.79 mm |
| Annual | 8.8 °C | 20 °C | 1275.33 mm |
| 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 : -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 |