Winslow, Illinois has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3 °C (low) to 14.5 °C (high). Annual precipitation averages 941.6 Millimeters. Winslow is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.6 °C | -2 °C | 33.53 mm |
| February | -9.7 °C | 0.4 °C | 37.85 mm |
| March | -3.7 °C | 7.3 °C | 49.28 mm |
| April | 2.2 °C | 14.9 °C | 92.96 mm |
| May | 8.7 °C | 21.4 °C | 104.14 mm |
| June | 14.3 °C | 26.7 °C | 141.99 mm |
| July | 16.3 °C | 28.3 °C | 109.47 mm |
| August | 15 °C | 27.4 °C | 101.35 mm |
| September | 10.3 °C | 23.8 °C | 97.03 mm |
| October | 4 °C | 16.7 °C | 75.18 mm |
| November | -2.1 °C | 8.1 °C | 56.13 mm |
| December | -7.9 °C | 1 °C | 42.67 mm |
| Annual | 3 °C | 14.5 °C | 941.58 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |