Ontario, WI Weather & Growing Conditions
Today
79°F
Mostly Cloudy then Isolated Rain Showers
Isolated rain showers after 4pm. Mostly cloudy. High near 79, with temperatures falling to around 74 in the afternoon. West wind 5 to 9 mph, with gusts as high as 18 mph. Chance of precipitation is 20%.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 79°F | Mostly Cloudy then Isolated Rain Showers | 5 to 9 mph W | 23% |
| Tonight | 59°F | Scattered Showers And Thunderstorms | 3 mph NW | 38% |
| Wednesday | 77°F | Partly Sunny | 3 mph NW | 7% |
| Wednesday Night | 54°F | Partly Cloudy | 0 to 3 mph SW | 1% |
| Thursday | 81°F | Sunny | 0 to 3 mph S | 1% |
| Thursday Night | 58°F | Mostly Clear | 3 mph SW | 0% |
| Friday | 84°F | Sunny | 2 to 9 mph SW | 4% |
| Friday Night | 62°F | Mostly Clear | 2 to 8 mph SW | 13% |
| Saturday | 85°F | Mostly Sunny | 3 to 8 mph SW | 13% |
| Saturday Night | 65°F | Partly Cloudy then Chance Rain Showers | 2 to 8 mph SW | 34% |
| Sunday | 85°F | Chance Rain Showers | 2 to 9 mph W | 34% |
| Sunday Night | 64°F | Chance Showers And Thunderstorms | 1 to 6 mph S | 43% |
| Monday | 83°F | Chance Rain Showers then Slight Chance Showers And Thunderstorms | 2 to 6 mph S | 43% |
| Monday Night | 63°F | Chance Showers And Thunderstorms | 1 to 6 mph N | 30% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Ontario, WI
Last spring frost
Apr 27
First fall frost
Oct 14
Growing season
170 days
Hardiness zone
4b
Explore more for Ontario, WI: full frost dates · planting calendar · Wisconsin frost dates
Climate data from the nearest NOAA station, Cashton, Wi (10.7 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.