Today | Weather | Tuesday, April 28, 2026
Active Weather Warnings

Weather in Janesville, Wisconsin

03:14 AM
Now
Cloudy Weather
50° F
Feels Like 43°
Precipitation 7 %
Wind 14 mph
Humidity 92 %
Today
Cloudy Weather
Day 63°
Night 43°
Precipitation 8 %
Wind 12 mph
UV Index (0 - 11+) 3

Janesville Weather Forecast Updated

Last updated on

Air Quality in Janesville

NOW
38 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 1.25 µg/m³
PM10 1.4 µg/m³
O3 0.041 ppm
NO2 0.6 ppb
SO2 0.1 ppb
CO 0.14 ppm
NH3 4.55 µg/m³
NO 0 µg/m³
PM2.5 – Fine particles <2.5μm
PM10 – Inhalable particles <10μm
O3 – Ozone
NO2 – Nitrogen dioxide
SO2 – Sulfur dioxide
CO – Carbon monoxide
NH3 – Ammonia
NO – Nitric oxide

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

Show raw pollutant concentrations (µg/m³)
PM2.51.25 µg/m³
PM101.4 µg/m³
O380.05 µg/m³
NO21.14 µg/m³
SO20.31 µg/m³
CO160.12 µg/m³
NH34.55 µg/m³
NO0 µg/m³

Weather Alerts and Warnings for Janesville

Severe Immediate Observed

Flood Warning

Flood Warning issued April 27 at 9:38PM CDT by NWS Milwaukee/Sullivan WI
Apr 27, 9:38 PM Apr 28, 9:45 AM
...The Flood Warning continues for the following rivers in
Wisconsin...Illinois...

Rock River At Fort Atkinson affecting Jefferson County.

Fox River Lower Near New Munster affecting Lake and Kenosha
Counties.

Rock River At Newville affecting Rock County.

Rock River Near Lake Koshkonong affecting Jefferson and Rock
Counties.

Rock River At Afton affecting Winnebago and Rock Counties.

Rock River At Jefferson affecting Jefferson County.

ROCK RIVER near LEBANON-3 E-HWY MM BRIDGE affecting Dodge County.

WHAT: Minor flooding is occurring and minor flooding is forecast.

WHERE: Rock River at Afton.

WHEN: Until further notice.

IMPACTS: At 10.5 feet, Floodwaters affect Riverside Park on the
north side of Janesville and South River Road on the south side of
Janesville. Floodwaters affect low spots on South River Rd on the
south side of Janesville. Floodwaters affect a home on South
Christian Rd on the east side of the river in the Afton area.
There is extensive lowland and agricultural land flooding in the
Afton and Janesville areas.

ADDITIONAL DETAILS:
- At 9:00 PM CDT Monday the stage was 10.6 feet.
- Bankfull stage is 8.0 feet.
- Recent Activity...The maximum river stage in the 24 hours
ending at 9:00 PM CDT Monday was 10.7 feet.
- Forecast...The river is expected to rise to a crest of 10.6
feet just after midnight tonight.
- Flood stage is 9.0 feet.
- Flood History...This crest compares to a previous crest of
10.6 feet on 04/12/1923.
- http://www.weather.gov/safety/flood
+ Read More
Caution is urged when walking near riverbanks. Motorists should not attempt to drive around barricades or drive cars through flooded areas. Additional information is available at www.weather.gov. The next statement will be issued Tuesday morning at 945 AM CDT.
Updated: Apr 28, 1:45 AM Source: NWS Alert