Bull Valley, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.8 °C (low) to 14.6 °C (high). Annual precipitation averages 976.9 Millimeters. Bull Valley 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 | -9.9 °C | -1.1 °C | 45.72 mm |
| February | -8.4 °C | 1.2 °C | 47.75 mm |
| March | -3.2 °C | 7.6 °C | 56.39 mm |
| April | 2.4 °C | 14.5 °C | 96.77 mm |
| May | 8.8 °C | 20.9 °C | 118.87 mm |
| June | 14.3 °C | 26.3 °C | 126.24 mm |
| July | 16.7 °C | 28.4 °C | 100.58 mm |
| August | 15.7 °C | 27.4 °C | 99.57 mm |
| September | 11.4 °C | 23.7 °C | 91.44 mm |
| October | 5.2 °C | 16.4 °C | 80.26 mm |
| November | -0.9 °C | 8.4 °C | 62.48 mm |
| December | -6.7 °C | 1.4 °C | 50.8 mm |
| Annual | 3.8 °C | 14.6 °C | 976.87 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 | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |