South Milwaukee, Wisconsin climate: Normal weather by month, frost dates and records
South Milwaukee's normal year runs from 16°F January nights to 80°F July afternoons, with 36.6 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 9.1°C, January lows of −9°C, July highs of 27°C, 929 mm of precipitation a year.
- NOAA stationSouth Milwaukee Wastewater Treatment Plant
- Station IDUSC00477964
- Location42.90°N 87.85°W
- Elevation650 ft (198 m)
- From the center1 miles
- Population20,233
On October 14, the normal high in South Milwaukee is 62°F and the normal low 45°F, and the chance of measurable rain or snow is 38%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for South Milwaukee.
- Jan 30° 16°
- Feb 33° 18°
- Mar 42° 28°
- Apr 53° 37°
- May 64° 47°
- Jun 75° 57°
- Jul 80° 65°
- Aug 79° 64°
- Sep 73° 56°
- Oct 61° 44°
- Nov 48° 33°
- Dec 36° 22°
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 South Milwaukee each month?
July is the warmest month, with normal highs of 80°F; January the coldest, with normal lows of 16°F. The most precipitation falls in June (4.58 in), the least in January (1.65 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 30°F | 16°F | 23.2°F | 1.65 | 10 | <1 | 29 | 9 h 20 min |
| February | 33°F | 18°F | 25.7°F | 1.84 | 9 | <1 | 26 | 10 h 30 min |
| March | 42°F | 28°F | 35.0°F | 2.20 | 10 | <1 | 21 | 11 h 50 min |
| April | 53°F | 37°F | 45.0°F | 4.08 | 13 | <1 | 7 | 13 h 20 min |
| May | 64°F | 47°F | 55.7°F | 4.18 | 14 | <1 | <1 | 14 h 40 min |
| June | 75°F | 57°F | 65.9°F | 4.58 | 13 | 1 | <1 | 15 h 20 min |
| July | 80°F | 65°F | 72.6°F | 3.51 | 9 | 3 | <1 | 15 h |
| August | 79°F | 64°F | 71.7°F | 3.80 | 11 | 2 | <1 | 14 h |
| September | 73°F | 56°F | 64.5°F | 3.30 | 10 | 1 | <1 | 12 h 30 min |
| October | 61°F | 44°F | 52.3°F | 3.40 | 12 | <1 | 3 | 11 h 10 min |
| November | 48°F | 33°F | 40.2°F | 2.14 | 9 | <1 | 14 | 9 h 50 min |
| December | 36°F | 22°F | 29.0°F | 1.90 | 11 | <1 | 25 | 9 h |
| Year (annual) | 56°F | 41°F | 48.4°F | 36.58 | 131 | 7 | 124 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | −1°C | −9°C | −4.9°C | 42 mm |
| February | 1°C | −8°C | −3.5°C | 47 mm |
| March | 6°C | −2°C | 1.7°C | 56 mm |
| April | 12°C | 3°C | 7.2°C | 104 mm |
| May | 18°C | 8°C | 13.2°C | 106 mm |
| June | 24°C | 14°C | 18.8°C | 116 mm |
| July | 27°C | 18°C | 22.6°C | 89 mm |
| August | 26°C | 18°C | 22.1°C | 97 mm |
| September | 23°C | 13°C | 18.1°C | 84 mm |
| October | 16°C | 7°C | 11.3°C | 86 mm |
| November | 9°C | 0°C | 4.6°C | 54 mm |
| December | 2°C | −5°C | −1.7°C | 48 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Milwaukee (5 miles away), gets 49 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00477964; 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 South Milwaukee?
Normal highs sit between 65°F and 85°F in 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 USC00477964.
When is the last frost in South Milwaukee?
In South Milwaukee, the last spring frost (32°F) comes after April 22 in half of years and after May 8 in one year in ten; the first autumn frost comes before October 26 in half of years and before October 10 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 221 year in 10 after May 8; 9 in 10 after April 9
- First autumn frost, half of years before
- October 261 year in 10 before October 10; 9 in 10 before November 8
NOAA puts the median frost-free season at 184 days, and the season without a hard freeze (28°F) at 208 days.
A hard freeze (28°F) comes after April 9 in half of springs and before November 5 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts South Milwaukee in zone 6a in ZIP code 53172.
Frost dates for every NOAA station in Wisconsin · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00477964; 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.
How hot and how cold does it get in South Milwaukee?
In a normal year in South Milwaukee, 7 days a year reach 90°F, 124 nights fall to 32°F or colder and 131 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
- 124a normal year
- Days that stay below freezing
- 50high of 32°F or less
- Days with 0.01 inch of precipitation
- 131a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00477964.
How sunny is South Milwaukee?
Over a year 70% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around South Milwaukee, 3.7 kWh per square metre a day. July is the sunniest month (79%) and January the cloudiest (53%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 53% | 1.4 |
| February | 58% | 2.3 |
| March | 65% | 3.4 |
| April | 67% | 4.5 |
| May | 68% | 5.3 |
| June | 74% | 5.9 |
| July | 79% | 6.0 |
| August | 78% | 5.2 |
| September | 77% | 4.2 |
| October | 67% | 2.7 |
| November | 62% | 1.8 |
| December | 54% | 1.2 |
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 South Milwaukee need?
A normal year in South Milwaukee brings 6,679 heating degree days, 24% more than the median U.S. place (5,373), and 661 cooling degree days, 27% fewer than the median (908). Eight months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 2,716 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,297 | 0 |
| February | 1,102 | 0 |
| March | 932 | 0 |
| April | 599 | 1 |
| May | 303 | 15 |
| June | 75 | 102 |
| July | 8 | 242 |
| August | 7 | 216 |
| September | 95 | 79 |
| October | 399 | 5 |
| November | 744 | 0 |
| December | 1,117 | 0 |
| Year (annual) | 6,679 | 661 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00477964. 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 South Milwaukee been warmer than normal lately?
2025 averaged 49.0°F, 0.6°F above the 1991-2020 normal of 48.4°F. 2 of the 3 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 49.7°F | +1.3°F | 25.02 |
| 2022 | 48.1°F | −0.3°F | 39.20 |
| 2025 | 49.0°F | +0.6°F | 32.62 |
Source: observed years: ACIS, station USC00477964. A year counts only with all twelve months complete.
How does South Milwaukee's climate compare?
South Milwaukee is warmer than 157 of the other 164 places with their own NOAA record in Wisconsin, and wetter than 120. Across the 7,247 U.S. stations with normals, its annual mean of 48.4°F is warmer than 34%.
In the Köppen classification computed from these normals, South Milwaukee is Dfa: continental, no dry season, hot 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 South Milwaukee share this climate record?
Oak Creek has no NOAA station with 1991-2020 normals of its 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.
- Oak Creek, WI38,373 people · 3 mi SW
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 South Milwaukee's climate
What is the coldest month in South Milwaukee?
January, with a normal high of 30°F and a normal low of 16°F. The warmest is July (80°F by day, 65°F at night).
Does it snow in South Milwaukee?
Yes. NOAA publishes no 1991-2020 snowfall normal for South Milwaukee's NOAA station; the nearest record that keeps one, Milwaukee (5 miles away), records 49 inches of snow in a normal year.
What is the rainiest month in South Milwaukee?
June, with 4.58 in of precipitation in a normal year; the driest is January with 1.65 in.
What plant hardiness zone is South Milwaukee in?
The USDA's 2023 map puts South Milwaukee in zone 6a in ZIP code 53172.
How late can frost come in South Milwaukee?
In half of years the last 32°F night comes after April 22; in one year in ten it comes after May 8. Waiting until May 8 leaves about a one-in-ten chance of a later frost.
Nearby and next
- Wisconsin climateThe statewide normals and every place in the state
- Milwaukee, WI4 miles from this station, 49.3°F a year
- Hales Corners, WI9 miles from this station, 47.3°F a year
- Racine, WI10 miles from this station, 48.4°F a year
- West Allis, WI11 miles from this station, 49.1°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made