Darien, 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 15.8 °C (high). Annual precipitation averages 1020.8 Millimeters. Darien is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.9 °C | 0.1 °C | 56.64 mm |
| February | -7.4 °C | 2.2 °C | 53.85 mm |
| March | -2.2 °C | 8.8 °C | 61.21 mm |
| April | 3.7 °C | 15.8 °C | 101.85 mm |
| May | 9.7 °C | 22 °C | 123.19 mm |
| June | 15.3 °C | 27.5 °C | 115.82 mm |
| July | 17.8 °C | 29.8 °C | 105.16 mm |
| August | 17 °C | 28.7 °C | 105.66 mm |
| September | 12.7 °C | 25.1 °C | 84.07 mm |
| October | 5.8 °C | 17.7 °C | 91.44 mm |
| November | -0.2 °C | 9.3 °C | 65.28 mm |
| December | -5.7 °C | 2.6 °C | 57.66 mm |
| Annual | 4.8 °C | 15.8 °C | 1021.83 mm |
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.9 °C | 0.1 °C | 56.39 mm |
| February | -7.5 °C | 2.1 °C | 53.59 mm |
| March | -2.2 °C | 8.8 °C | 61.21 mm |
| April | 3.6 °C | 15.8 °C | 101.85 mm |
| May | 9.6 °C | 22 °C | 123.19 mm |
| June | 15.2 °C | 27.4 °C | 116.33 mm |
| July | 17.7 °C | 29.7 °C | 104.65 mm |
| August | 16.9 °C | 28.6 °C | 105.16 mm |
| September | 12.6 °C | 25.1 °C | 84.07 mm |
| October | 5.8 °C | 17.6 °C | 91.69 mm |
| November | -0.3 °C | 9.3 °C | 65.28 mm |
| December | -5.8 °C | 2.5 °C | 57.4 mm |
| Annual | 4.7 °C | 15.8 °C | 1020.81 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 |