Hainesville, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4 °C (low) to 14.2 °C (high). Annual precipitation averages 966 Millimeters. Hainesville is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.8 °C | -1.3 °C | 48.77 mm |
| February | -8.3 °C | 0.8 °C | 49.78 mm |
| March | -3.1 °C | 6.9 °C | 58.17 mm |
| April | 2.7 °C | 13.9 °C | 98.81 mm |
| May | 8.7 °C | 20.2 °C | 113.79 mm |
| June | 14.3 °C | 25.7 °C | 116.84 mm |
| July | 17.1 °C | 28.1 °C | 96.77 mm |
| August | 16.3 °C | 27.2 °C | 95.76 mm |
| September | 11.9 °C | 23.3 °C | 90.17 mm |
| October | 5.5 °C | 16.2 °C | 81.28 mm |
| November | -0.7 °C | 8.3 °C | 61.47 mm |
| December | -6.4 °C | 1.6 °C | 54.36 mm |
| Annual | 4 °C | 14.2 °C | 965.97 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |