Janesville, IA Weather & Growing Conditions
Today
77°F
Showers And Thunderstorms
Showers and thunderstorms. Partly sunny. High near 77, with temperatures falling to around 75 in the afternoon. West northwest wind around 10 mph. Chance of precipitation is 80%. New rainfall amounts less than a tenth of an inch possible.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 77°F | Showers And Thunderstorms | 10 mph WNW | 79% |
| Tonight | 60°F | Showers And Thunderstorms Likely | 5 to 8 mph N | 63% |
| Wednesday | 73°F | Chance Showers And Thunderstorms then Partly Sunny | 5 mph NNE | 30% |
| Wednesday Night | 54°F | Mostly Clear | 1 to 5 mph N | 12% |
| Thursday | 78°F | Sunny | 0 to 5 mph E | 1% |
| Thursday Night | 59°F | Mostly Clear | 3 mph SSE | 0% |
| Friday | 81°F | Sunny | 2 to 12 mph SSE | 7% |
| Friday Night | 65°F | Mostly Clear | 6 to 9 mph S | 12% |
| Saturday | 84°F | Sunny | 5 to 10 mph S | 9% |
| Saturday Night | 69°F | Chance Showers And Thunderstorms | 9 to 13 mph S | 28% |
| Sunday | 85°F | Chance Showers And Thunderstorms | 12 mph SSW | 28% |
| Sunday Night | 68°F | Chance Showers And Thunderstorms | 9 mph SSE | 35% |
| Monday | 84°F | Chance Showers And Thunderstorms then Slight Chance Showers And Thunderstorms | 8 to 12 mph SSE | 35% |
| Monday Night | 68°F | Slight Chance Showers And Thunderstorms | 8 to 12 mph ENE | 36% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Janesville, IA
Last spring frost
Apr 27
First fall frost
Oct 10
Growing season
165 days
Hardiness zone
5a
Explore more for Janesville, IA: full frost dates · planting calendar · Iowa frost dates
Climate data from the nearest NOAA station, Waterloo Muni Ap, Ia (8.3 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.