Brookfield, Wisconsin climate: Normal weather by month, frost dates and records
Brookfield's normal year runs from 12°F January nights to 81°F July afternoons, with 35.9 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 8.1°C, January lows of −11°C, July highs of 27°C, 912 mm of precipitation a year.
- NOAA stationBrookfield Wastewater Treatment Plant
- Station IDUSC00471062
- Location43.05°N 88.18°W
- Elevation830 ft (253 m)
- From the center3 miles
- Population41,268
On October 14, the normal high in Brookfield is 60°F and the normal low 41°F, and the chance of measurable rain or snow is 41%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Brookfield.
- Jan 28° 12°
- Feb 32° 15°
- Mar 42° 25°
- Apr 54° 35°
- May 67° 47°
- Jun 77° 56°
- Jul 81° 61°
- Aug 79° 60°
- Sep 72° 51°
- Oct 59° 40°
- Nov 45° 29°
- Dec 33° 19°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Brookfield each month?
July is the warmest month, with normal highs of 81°F; January the coldest, with normal lows of 12°F. The most precipitation falls in June (4.80 in), the least in February (1.56 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 28°F | 12°F | 19.9°F | 1.59 | 11 | <1 | 30 | 9 h 20 min |
| February | 32°F | 15°F | 23.3°F | 1.56 | 11 | <1 | 27 | 10 h 30 min |
| March | 42°F | 25°F | 33.5°F | 2.06 | 9 | <1 | 24 | 11 h 50 min |
| April | 54°F | 35°F | 44.5°F | 3.71 | 13 | <1 | 12 | 13 h 20 min |
| May | 67°F | 47°F | 56.5°F | 3.94 | 14 | <1 | 1 | 14 h 40 min |
| June | 77°F | 56°F | 66.3°F | 4.80 | 12 | 1 | <1 | 15 h 20 min |
| July | 81°F | 61°F | 71.3°F | 3.82 | 9 | 3 | <1 | 15 h |
| August | 79°F | 60°F | 69.7°F | 3.97 | 11 | 1 | <1 | 14 h |
| September | 72°F | 51°F | 61.8°F | 3.21 | 10 | 1 | <1 | 12 h 30 min |
| October | 59°F | 40°F | 49.8°F | 3.09 | 13 | <1 | 6 | 11 h 10 min |
| November | 45°F | 29°F | 36.8°F | 2.19 | 10 | <1 | 21 | 9 h 50 min |
| December | 33°F | 19°F | 25.9°F | 1.96 | 12 | <1 | 28 | 9 h |
| Year (annual) | 56°F | 37°F | 46.6°F | 35.90 | 135 | 7 | 149 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | −2°C | −11°C | −6.7°C | 40 mm |
| February | 0°C | −9°C | −4.8°C | 40 mm |
| March | 6°C | −4°C | 0.8°C | 52 mm |
| April | 12°C | 2°C | 6.9°C | 94 mm |
| May | 19°C | 8°C | 13.6°C | 100 mm |
| June | 25°C | 13°C | 19.1°C | 122 mm |
| July | 27°C | 16°C | 21.8°C | 97 mm |
| August | 26°C | 16°C | 20.9°C | 101 mm |
| September | 22°C | 11°C | 16.6°C | 82 mm |
| October | 15°C | 5°C | 9.9°C | 78 mm |
| November | 7°C | −2°C | 2.7°C | 56 mm |
| December | 1°C | −7°C | −3.4°C | 50 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Waukesha (5 miles away), gets 37 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00471062; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Brookfield?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, July has the fewest days with rain (9).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00471062.
When is the last frost in Brookfield?
In Brookfield, the last spring frost (32°F) comes after April 30 in half of years and after May 15 in one year in ten; the first autumn frost comes before October 14 in half of years and before September 28 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- April 301 year in 10 after May 15; 9 in 10 after April 16
- First autumn frost, half of years before
- October 141 year in 10 before September 28; 9 in 10 before October 27
NOAA puts the median frost-free season at 164 days, and the season without a hard freeze (28°F) at 188 days.
A hard freeze (28°F) comes after April 19 in half of springs and before October 25 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Brookfield in zone 5b across its 2 ZIP code areas (5b in 53005, the largest).
Frost dates for every NOAA station in Wisconsin · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00471062; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
What hardiness zone is each Brookfield ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Brookfield's 2 ZIP code areas are all in zone 5b. Each ZIP's frost dates are in the frost tool.
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in Brookfield?
In a normal year in Brookfield, 7 days a year reach 90°F, 149 nights fall to 32°F or colder and 135 days bring measurable precipitation.
- Days at 90°F or more
- 7a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 149a normal year
- Days that stay below freezing
- 65high of 32°F or less
- Days with 0.01 inch of precipitation
- 135a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00471062.
How sunny is Brookfield?
Over a year 72% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Brookfield, 3.8 kWh per square metre a day. July is the sunniest month (80%) and December the cloudiest (59%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 63% | 1.6 |
| February | 70% | 2.7 |
| March | 70% | 3.7 |
| April | 68% | 4.6 |
| May | 71% | 5.5 |
| June | 76% | 6.1 |
| July | 80% | 6.3 |
| August | 78% | 5.3 |
| September | 77% | 4.2 |
| October | 68% | 2.7 |
| November | 66% | 1.8 |
| December | 59% | 1.3 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Brookfield need?
A normal year in Brookfield brings 7,243 heating degree days, 35% more than the median U.S. place (5,373), and 577 cooling degree days, 36% fewer than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 2,550 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,396 | 0 |
| February | 1,169 | 0 |
| March | 978 | 1 |
| April | 615 | 2 |
| May | 291 | 29 |
| June | 68 | 106 |
| July | 14 | 209 |
| August | 22 | 168 |
| September | 155 | 57 |
| October | 477 | 6 |
| November | 846 | 0 |
| December | 1,212 | 0 |
| Year (annual) | 7,243 | 577 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00471062. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Brookfield been warmer than normal lately?
2025 averaged 46.9°F, 0.3°F above the 1991-2020 normal of 46.6°F. 2 of the 2 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 48.4°F | +1.8°F | 28.35 |
| 2025 | 46.9°F | +0.3°F | 38.51 |
Source: observed years: ACIS, station USC00471062. A year counts only with all twelve months complete.
How does Brookfield's climate compare?
Brookfield is warmer than 123 of the other 164 places with their own NOAA record in Wisconsin, and wetter than 108. Across the 7,247 U.S. stations with normals, its annual mean of 46.6°F is warmer than 26%.
In the Köppen classification computed from these normals, Brookfield is Dfb: continental, no dry season, warm summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Brookfield share this climate record?
2 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Pewaukee, WI16,437 people · 4 mi W
- Pewaukee, WI8,230 people · 5 mi NW
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Brookfield's climate
What is the coldest month in Brookfield?
January, with a normal high of 28°F and a normal low of 12°F. The warmest is July (81°F by day, 61°F at night).
Does it snow in Brookfield?
Yes. NOAA publishes no 1991-2020 snowfall normal for Brookfield's NOAA station; the nearest record that keeps one, Waukesha (5 miles away), records 37 inches of snow in a normal year.
What is the rainiest month in Brookfield?
June, with 4.80 in of precipitation in a normal year; the driest is February with 1.56 in.
What plant hardiness zone is Brookfield in?
The USDA's 2023 map puts Brookfield in zone 5b across its 2 ZIP code areas (5b in 53005, the largest).
How late can frost come in Brookfield?
In half of years the last 32°F night comes after April 30; in one year in ten it comes after May 15. Waiting until May 15 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Brookfield in OctoberThis month day by day, its records and recent years
- Wisconsin climateThe statewide normals and every place in the state
- Waukesha, WI5 miles from this station, 46.5°F a year
- Wauwatosa, WI7 miles from this station, 48.2°F a year
- West Allis, WI9 miles from this station, 49.1°F a year
- Hales Corners, WI11 miles from this station, 47.3°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made