Washburn, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.7 °C (low) to 16.1 °C (high). Annual precipitation averages 958.4 Millimeters. Washburn 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 | -9.3 °C | -0.1 °C | 52.07 mm |
| February | -7.4 °C | 2.4 °C | 48.26 mm |
| March | -1.9 °C | 9.3 °C | 65.28 mm |
| April | 3.9 °C | 16.7 °C | 94.74 mm |
| May | 10.4 °C | 22.7 °C | 119.13 mm |
| June | 15.8 °C | 27.7 °C | 106.43 mm |
| July | 17.7 °C | 29.3 °C | 96.27 mm |
| August | 16.5 °C | 28.5 °C | 92.46 mm |
| September | 11.9 °C | 25.5 °C | 87.88 mm |
| October | 5.5 °C | 18.3 °C | 76.71 mm |
| November | -0.7 °C | 9.9 °C | 67.31 mm |
| December | -6.1 °C | 2.8 °C | 51.82 mm |
| Annual | 4.7 °C | 16.1 °C | 958.36 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 |