Ontario, OR Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Ontario, a city in Payette County, Oregon.
This Afternoon
78°F
Mostly Sunny
Mostly sunny, with a high near 78. South southeast wind around 3 mph.
7-day forecast for Ontario
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 78°F | Mostly Sunny | 3 mph SSE | 5% |
| Tonight | 54°F | Slight Chance Showers And Thunderstorms | 1 to 5 mph NW | 19% |
| Saturday | 81°F | Sunny | 3 mph NW | 4% |
| Saturday Night | 53°F | Mostly Clear | 2 mph N | 0% |
| Sunday | 83°F | Sunny | 2 mph SSE | 0% |
| Sunday Night | 54°F | Mostly Clear | 1 mph NNE | 0% |
| Monday | 84°F | Sunny | 2 mph ENE | 0% |
| Monday Night | 55°F | Mostly Clear | 1 mph N | 0% |
| Tuesday | 85°F | Sunny | 1 mph E | 0% |
| Tuesday Night | 54°F | Mostly Clear | 1 mph NNE | 1% |
| Wednesday | 84°F | Sunny | 2 mph E | 0% |
| Wednesday Night | 54°F | Mostly Clear | 1 mph N | 1% |
| Thursday | 87°F | Sunny | 0 to 3 mph NE | 0% |
| Thursday Night | 56°F | Partly Cloudy | 2 mph SE | 0% |
Forecast source: National Weather Service (api.weather.gov) for Ontario (44.025, -116.979). Updated through the day.
Growing snapshot for Ontario
Last spring frost
Apr 23
First fall frost
Oct 13
Growing season
173 days
Hardiness zone
7a
More local growing data for Ontario: nearby ZIP 83619 weather · frost dates · planting calendar · Oregon frost dates
Climate data from the nearest NOAA station, Malheur Branch Exp Stn, Or (5.7 mi from Ontario). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.