National Weather Service Forecast for: Janesville WI
Issued by: National Weather Service Milwaukee, WI
Updated: 1:21 am CDT Apr 6, 2026
 
Overnight

Overnight: Mostly cloudy early, then becoming mostly clear, with a low around 34. Northwest wind around 10 mph.
Mostly Clear

 Monday

Monday: Partly sunny, with a high near 45. Northwest wind 10 to 15 mph, with gusts as high as 25 mph.
Partly Sunny

 Monday
Night
Monday Night: Partly cloudy, with a low around 22. Northeast wind 5 to 10 mph.
Partly Cloudy

 Tuesday

Tuesday: Mostly sunny, with a high near 41. Northeast wind around 5 mph becoming southeast in the afternoon.
Mostly Sunny

 Tuesday
Night
Tuesday Night: A slight chance of snow before 1am, then a chance of rain and snow between 1am and 4am, then a chance of rain after 4am. Increasing clouds, with a low around 30. Southeast wind 5 to 10 mph. Chance of precipitation is 40%.
Slight Chance
Snow then
Chance
Rain/Snow
 Wednesday

Wednesday: Cloudy, then gradually becoming mostly sunny, with a high near 63. Breezy, with a south wind 15 to 20 mph, with gusts as high as 30 mph.
Mostly Cloudy
then Partly
Sunny and
Breezy
 Wednesday
Night
Wednesday Night: Showers likely, with thunderstorms also possible after 10pm. Mostly cloudy, with a low around 50. South wind around 15 mph, with gusts as high as 30 mph. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Showers
Likely

 Thursday

Thursday: A 50 percent chance of showers. Mostly cloudy, with a high near 63. Southwest wind 10 to 15 mph.
Chance
Showers

 Thursday
Night
Thursday Night: A 50 percent chance of showers. Mostly cloudy, with a low around 43.
Chance
Showers
Lo 34 °F Hi 45 °F Lo 22 °F Hi 41 °F Lo 30 °F Hi 63 °F Lo 50 °F Hi 63 °F Lo 43 °F

Hazardous Weather Outlook
 

Overnight
 
 Mostly cloudy early, then becoming mostly clear, with a low around 34. Northwest wind around 10 mph.
Monday
 
 Partly sunny, with a high near 45. Northwest wind 10 to 15 mph, with gusts as high as 25 mph.
Monday Night
 
 Partly cloudy, with a low around 22. Northeast wind 5 to 10 mph.
Tuesday
 
 Mostly sunny, with a high near 41. Northeast wind around 5 mph becoming southeast in the afternoon.
Tuesday Night
 
 A slight chance of snow before 1am, then a chance of rain and snow between 1am and 4am, then a chance of rain after 4am. Increasing clouds, with a low around 30. Southeast wind 5 to 10 mph. Chance of precipitation is 40%.
Wednesday
 
 Cloudy, then gradually becoming mostly sunny, with a high near 63. Breezy, with a south wind 15 to 20 mph, with gusts as high as 30 mph.
Wednesday Night
 
 Showers likely, with thunderstorms also possible after 10pm. Mostly cloudy, with a low around 50. South wind around 15 mph, with gusts as high as 30 mph. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Thursday
 
 A 50 percent chance of showers. Mostly cloudy, with a high near 63. Southwest wind 10 to 15 mph.
Thursday Night
 
 A 50 percent chance of showers. Mostly cloudy, with a low around 43.
Friday
 
 A 20 percent chance of showers. Mostly sunny, with a high near 59.
Friday Night
 
 A 30 percent chance of showers. Partly cloudy, with a low around 39.
Saturday
 
 A 30 percent chance of showers. Partly sunny, with a high near 60.
Saturday Night
 
 A 50 percent chance of showers. Mostly cloudy, with a low around 50.
Sunday
 
 Showers likely and possibly a thunderstorm. Mostly cloudy, with a high near 74. Chance of precipitation is 60%.

 

Forecast from NOAA-NWS for Janesville WI.