South Beloit, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.5 °C (low) to 14.3 °C (high). Annual precipitation averages 952.5 Millimeters. South Beloit 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 | -10.9 °C | -2.1 °C | 40.89 mm |
| February | -9.2 °C | 0.2 °C | 39.62 mm |
| March | -3.4 °C | 7 °C | 53.34 mm |
| April | 2.6 °C | 14.3 °C | 93.22 mm |
| May | 9 °C | 20.8 °C | 109.98 mm |
| June | 14.6 °C | 26.4 °C | 139.95 mm |
| July | 16.8 °C | 28.3 °C | 93.47 mm |
| August | 15.8 °C | 27.5 °C | 104.9 mm |
| September | 11.1 °C | 23.8 °C | 96.27 mm |
| October | 4.7 °C | 16.4 °C | 73.15 mm |
| November | -1.6 °C | 8 °C | 58.93 mm |
| December | -7.2 °C | 1.1 °C | 48.77 mm |
| Annual | 3.5 °C | 14.3 °C | 952.49 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 |