Brookfield, Wisconsin has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 37.7 °F (low) to 56.4 °F (high). Annual precipitation averages 35.6 Inches. Brookfield 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 12.6 °F | 28.2 °F | 1.72 in. |
| February | 15.5 °F | 31.9 °F | 1.61 in. |
| March | 24.7 °F | 42.8 °F | 2.01 in. |
| April | 35.4 °F | 55.2 °F | 3.84 in. |
| May | 46.2 °F | 67.0 °F | 4.02 in. |
| June | 56.2 °F | 76.9 °F | 4.78 in. |
| July | 61.4 °F | 81.7 °F | 3.85 in. |
| August | 59.9 °F | 80.1 °F | 3.74 in. |
| September | 51.7 °F | 73.1 °F | 3.15 in. |
| October | 40.4 °F | 60.2 °F | 2.82 in. |
| November | 29.4 °F | 45.9 °F | 2.07 in. |
| December | 19.1 °F | 33.7 °F | 2.01 in. |
| Annual | 37.7 °F | 56.4 °F | 35.62 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |