Janesville, WI Weather & Growing Conditions
Tonight
61°F
Chance Showers And Thunderstorms then Showers And Thunderstorms
A chance of showers and thunderstorms before 11pm, then showers and thunderstorms. Cloudy, with a low around 61. East wind 5 to 10 mph. Chance of precipitation is 90%. New rainfall amounts between three quarters and one inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 61°F | Chance Showers And Thunderstorms then Showers And Thunderstorms | 5 to 10 mph E | 91% |
| Sunday | 65°F | Showers And Thunderstorms Likely then Cloudy | 10 to 15 mph NE | 65% |
| Sunday Night | 53°F | Mostly Cloudy | 10 to 15 mph NE | 3% |
| Monday | 62°F | Cloudy then Chance Rain Showers | 15 mph NE | 28% |
| Monday Night | 48°F | Chance Rain Showers | 10 to 15 mph NE | 50% |
| Tuesday | 60°F | Chance Rain Showers | 10 to 15 mph NE | 50% |
| Tuesday Night | 47°F | Mostly Cloudy | 5 to 10 mph NE | 9% |
| Wednesday | 62°F | Partly Sunny | 5 to 15 mph NE | 6% |
| Wednesday Night | 48°F | Mostly Cloudy | 5 to 10 mph NE | 3% |
| Thursday | 65°F | Partly Sunny | 5 mph NE | 8% |
| Thursday Night | 50°F | Mostly Cloudy | 0 to 5 mph NE | 10% |
| Friday | 69°F | Partly Sunny | 0 to 5 mph NE | 8% |
| Friday Night | 50°F | Partly Cloudy | 0 to 5 mph NE | 8% |
| Saturday | 70°F | Mostly Sunny | 0 to 5 mph E | 6% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Janesville, WI
Last spring frost
Apr 26
First fall frost
Oct 15
Growing season
170 days
Hardiness zone
5b
Explore more for Janesville, WI: full frost dates · planting calendar · Wisconsin frost dates
Climate data from the nearest NOAA station, Afton - Janesville Wwtp, Wi (6 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 20, 2026.