Janesville, WI Weather & Growing Conditions
This Afternoon
69°F
Scattered Showers And Thunderstorms
Scattered showers and thunderstorms before 5pm, then a chance of showers and thunderstorms. Cloudy, with a high near 69. Southeast wind around 5 mph. Chance of precipitation is 40%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 69°F | Scattered Showers And Thunderstorms | 5 mph SE | 39% |
| Tonight | 61°F | Chance Showers And Thunderstorms then Showers And Thunderstorms | 5 to 10 mph NE | 89% |
| Sunday | 64°F | Chance Rain Showers then Cloudy | 15 mph NE | 63% |
| Sunday Night | 54°F | Mostly Cloudy | 10 to 15 mph NE | 3% |
| Monday | 62°F | Mostly Cloudy then Chance Rain Showers | 15 mph NE | 30% |
| Monday Night | 49°F | Chance Rain Showers | 10 to 15 mph NE | 49% |
| Tuesday | 60°F | Chance Rain Showers | 10 to 15 mph NE | 49% |
| Tuesday Night | 48°F | Mostly Cloudy | 5 to 10 mph NE | 10% |
| Wednesday | 62°F | Partly Sunny | 10 to 15 mph NE | 6% |
| Wednesday Night | 50°F | Mostly Cloudy | 5 to 10 mph NE | 3% |
| Thursday | 65°F | Partly Sunny | 5 mph NE | 9% |
| Thursday Night | 52°F | Mostly Cloudy | 0 to 5 mph NE | 10% |
| Friday | 69°F | Partly Sunny | 0 to 5 mph NE | 9% |
| Friday Night | 51°F | Partly Cloudy | 0 to 5 mph NE | 9% |
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 (4.9 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 20, 2026.