South Milwaukee, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 4.9 °C (low) to 13.2 °C (high). Annual precipitation averages 929.6 Millimeters. South Milwaukee 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 | -8.9 °C | -1.1 °C | 46.48 mm |
| February | -7.3 °C | 0.5 °C | 43.94 mm |
| March | -2.5 °C | 5.8 °C | 54.36 mm |
| April | 2.9 °C | 11.4 °C | 108.2 mm |
| May | 8.6 °C | 17.7 °C | 108.46 mm |
| June | 14.4 °C | 23.4 °C | 116.84 mm |
| July | 18 °C | 26.6 °C | 87.38 mm |
| August | 17.8 °C | 26 °C | 93.22 mm |
| September | 13.4 °C | 22.3 °C | 82.3 mm |
| October | 6.8 °C | 15.6 °C | 78.99 mm |
| November | 0.4 °C | 8.4 °C | 59.18 mm |
| December | -5.4 °C | 1.8 °C | 50.29 mm |
| Annual | 4.9 °C | 13.2 °C | 929.64 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 | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |