Deerfield, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.5 °C (low) to 14.6 °C (high). Annual precipitation averages 982.5 Millimeters. Deerfield is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.1 °C | -0.5 °C | 55.88 mm |
| February | -6.6 °C | 1.6 °C | 51.31 mm |
| March | -1.7 °C | 7.1 °C | 56.9 mm |
| April | 3.8 °C | 13.6 °C | 97.79 mm |
| May | 9.8 °C | 20.1 °C | 115.82 mm |
| June | 15.3 °C | 25.7 °C | 109.73 mm |
| July | 18.6 °C | 28.3 °C | 94.49 mm |
| August | 18.1 °C | 27.3 °C | 101.35 mm |
| September | 13.8 °C | 23.7 °C | 92.46 mm |
| October | 7.1 °C | 16.8 °C | 86.61 mm |
| November | 0.7 °C | 8.8 °C | 65.02 mm |
| December | -4.8 °C | 2.6 °C | 55.12 mm |
| Annual | 5.5 °C | 14.6 °C | 982.48 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°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 |