National Weather Service Forecast for: Janesville WI
Issued by: National Weather Service Milwaukee, WI
Updated: 3:32 am CDT Jun 22, 2026
 
Today

Today: Mostly sunny, with a high near 76. Northeast wind 5 to 10 mph.
Mostly Sunny

 Tonight

Tonight: Mostly clear, with a low around 51. Northeast wind around 5 mph becoming calm in the evening.
Mostly Clear

 Tuesday

Tuesday: Mostly sunny, with a high near 77. Calm wind becoming east around 5 mph.
Mostly Sunny

 Tuesday
Night
Tuesday Night: A 40 percent chance of showers after 1am. Mostly cloudy, with a low around 58. Calm wind becoming south around 5 mph after midnight.
Mostly Cloudy
then Chance
Showers
 Wednesday

Wednesday: Showers likely, with thunderstorms also possible after 1pm. Partly sunny, with a high near 78. South wind 5 to 10 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Showers
Likely
 Wednesday
Night
Wednesday Night: A chance of showers and thunderstorms before 10pm, then a chance of showers between 10pm and 1am. Partly cloudy, with a low around 57. West wind 5 to 10 mph becoming light in the evening. Chance of precipitation is 30%.
Chance
Showers
 Thursday

Thursday: Mostly sunny, with a high near 76. Northwest wind 5 to 10 mph.
Mostly Sunny

 Thursday
Night
Thursday Night: Mostly clear, with a low around 55. Northwest wind around 5 mph becoming calm in the evening.
Mostly Clear

 Friday

Friday: Mostly sunny, with a high near 78.
Mostly Sunny
Hi 76 °F Lo 51 °F Hi 77 °F Lo 58 °F Hi 78 °F Lo 57 °F Hi 76 °F Lo 55 °F Hi 78 °F

 

Today
 
 Mostly sunny, with a high near 76. Northeast wind 5 to 10 mph.
Tonight
 
 Mostly clear, with a low around 51. Northeast wind around 5 mph becoming calm in the evening.
Tuesday
 
 Mostly sunny, with a high near 77. Calm wind becoming east around 5 mph.
Tuesday Night
 
 A 40 percent chance of showers after 1am. Mostly cloudy, with a low around 58. Calm wind becoming south around 5 mph after midnight.
Wednesday
 
 Showers likely, with thunderstorms also possible after 1pm. Partly sunny, with a high near 78. South wind 5 to 10 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Wednesday Night
 
 A chance of showers and thunderstorms before 10pm, then a chance of showers between 10pm and 1am. Partly cloudy, with a low around 57. West wind 5 to 10 mph becoming light in the evening. Chance of precipitation is 30%.
Thursday
 
 Mostly sunny, with a high near 76. Northwest wind 5 to 10 mph.
Thursday Night
 
 Mostly clear, with a low around 55. Northwest wind around 5 mph becoming calm in the evening.
Friday
 
 Mostly sunny, with a high near 78.
Friday Night
 
 Mostly cloudy, with a low around 58.
Saturday
 
 Partly sunny, with a high near 80.
Saturday Night
 
 A 30 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 62.
Sunday
 
 A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 86.

 

Forecast from NOAA-NWS for Janesville WI.