Darien, Wisconsin has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.2 °C (low) to 14 °C (high). Annual precipitation averages 950.5 Millimeters. Darien is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.6 °C | -2 °C | 41.4 mm |
| February | -9.1 °C | 0.1 °C | 41.91 mm |
| March | -3.8 °C | 6.7 °C | 54.36 mm |
| April | 1.9 °C | 14.1 °C | 95.25 mm |
| May | 8.5 °C | 20.4 °C | 108.2 mm |
| June | 13.8 °C | 25.8 °C | 135.89 mm |
| July | 16.1 °C | 27.8 °C | 93.22 mm |
| August | 15.2 °C | 27 °C | 105.16 mm |
| September | 10.8 °C | 23.3 °C | 90.93 mm |
| October | 4.3 °C | 16.1 °C | 74.42 mm |
| November | -1.6 °C | 7.9 °C | 61.21 mm |
| December | -7.3 °C | 0.9 °C | 48.51 mm |
| Annual | 3.2 °C | 14 °C | 950.46 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| 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 |