| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F |
| 2012 Hardiness Zone: | Zone 5b: -15°F to -10°F |
| 1990 Hardiness Zone: | Zone 1b: -15F to -10F |
| Average First Frost Date: | Oct. 21 - Oct. 31 |
| Average Last Frost Date: | May 1 - May 10 |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year |
| Ecoregion: | 53b - Kettle Moraines |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 53172 - South Milwaukee, WI | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 13 | 18 | 27 | 37 | 46 | 56 | 63 | 62 | 54 | 42 | 31 | 19 | 39 |
| Avg Max Temp (°F) | 28 | 32 | 42 | 54 | 66 | 76 | 81 | 79 | 72 | 60 | 46 | 33 | 56 |
| Avg Precip (In.) | 1.77 | 1.6 | 2.49 | 3.75 | 3.06 | 3.61 | 3.62 | 4.06 | 3.36 | 2.49 | 2.69 | 2.17 | 34.65 |