Janesville, IL Weather & Growing Conditions
Tonight
69°F
Partly Cloudy
Partly cloudy, with a low around 69. Southeast wind around 7 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 69°F | Partly Cloudy | 7 mph SE | 7% |
| Saturday | 92°F | Slight Chance Showers And Thunderstorms then Chance Showers And Thunderstorms | 9 mph SSW | 27% |
| Saturday Night | 70°F | Mostly Cloudy then Slight Chance Showers And Thunderstorms | 5 to 8 mph S | 15% |
| Sunday | 89°F | Chance Showers And Thunderstorms | 5 to 9 mph WNW | 29% |
| Sunday Night | 63°F | Chance Showers And Thunderstorms | 10 mph NNE | 52% |
| Monday | 75°F | Showers And Thunderstorms Likely | 12 mph NE | 61% |
| Monday Night | 56°F | Showers And Thunderstorms Likely | 9 to 14 mph NE | 60% |
| Tuesday | 70°F | Chance Showers And Thunderstorms then Mostly Cloudy | 13 mph NNE | 37% |
| Tuesday Night | 53°F | Mostly Cloudy | 7 to 12 mph NNE | 8% |
| Wednesday | 71°F | Partly Sunny | 9 mph NNE | 3% |
| Wednesday Night | 54°F | Partly Cloudy | 5 to 8 mph NNE | 3% |
| Thursday | 73°F | Mostly Sunny | 8 mph NNE | 3% |
| Thursday Night | 55°F | Partly Cloudy | 7 mph NNE | 4% |
| Friday | 74°F | Mostly Sunny | 5 to 8 mph NNE | 4% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Janesville, IL
Last spring frost
Apr 15
First fall frost
Oct 24
Growing season
189 days
Hardiness zone
6a
Explore more for Janesville, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Mattoon Coles Co Ap, Il (5.9 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.