Byron, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.7 °C (low) to 14.5 °C (high). Annual precipitation averages 960.1 Millimeters. Byron 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 | -1.9 °C | 42.16 mm |
| February | -9.1 °C | 0.4 °C | 42.93 mm |
| March | -3.1 °C | 7.4 °C | 56.64 mm |
| April | 2.9 °C | 15 °C | 94.74 mm |
| May | 9.5 °C | 21.3 °C | 115.82 mm |
| June | 15.1 °C | 26.5 °C | 131.83 mm |
| July | 17 °C | 28.2 °C | 110.24 mm |
| August | 15.8 °C | 27.3 °C | 103.12 mm |
| September | 11.2 °C | 23.9 °C | 86.87 mm |
| October | 4.7 °C | 16.7 °C | 74.42 mm |
| November | -1.5 °C | 8.2 °C | 52.58 mm |
| December | -7.3 °C | 1.2 °C | 48.77 mm |
| Annual | 3.7 °C | 14.5 °C | 960.12 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 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |