| 2023 Hardiness Zone: | Zone 5b: -15°F to -10°F |
| 2012 Hardiness Zone: | Zone 5b: -15°F to -10°F |
| 1990 Hardiness Zone: | Zone 1b: -15F to -10F |
| Average First Frost Date: | Oct. 11 - Oct. 20 |
| Average Last Frost Date: | May 11 - May 20 |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers |
| Ecoregion: | 53b - Kettle Moraines |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 53005 - Brookfield, WI | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 12 | 16 | 26 | 37 | 47 | 57 | 63 | 61 | 52 | 41 | 30 | 18 | 38 |
| Avg Max Temp (°F) | 27 | 32 | 43 | 55 | 68 | 78 | 83 | 80 | 73 | 60 | 45 | 32 | 56 |
| Avg Precip (In.) | 1.52 | 1.32 | 2.13 | 3.51 | 2.95 | 3.66 | 3.67 | 4.12 | 3.43 | 2.41 | 2.49 | 1.89 | 33.09 |