Ontario, OR Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Ontario, a city in Payette County, Oregon.
This Afternoon
57°F
Mostly Cloudy
Mostly cloudy, with a high near 57. North wind around 3 mph.
7-day forecast for Ontario
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 57°F | Mostly Cloudy | 3 mph N | 2% |
| Tonight | 35°F | Mostly Cloudy | 2 mph WNW | 12% |
| Wednesday | 60°F | Sunny | 2 mph WNW | 1% |
| Wednesday Night | 35°F | Mostly Cloudy then Slight Chance Rain Showers | 1 mph E | 16% |
| Thursday | 56°F | Slight Chance Rain Showers then Partly Sunny | 2 mph N | 16% |
| Thursday Night | 31°F | Mostly Clear | 1 mph NNE | 1% |
| Friday | 55°F | Partly Sunny | 1 mph ENE | 1% |
| Friday Night | 32°F | Partly Cloudy | 0 mph | 1% |
| Saturday | 59°F | Mostly Sunny | 2 mph ENE | 1% |
| Saturday Night | 36°F | Partly Cloudy | 2 mph E | 0% |
| Sunday | 61°F | Mostly Sunny | 1 mph S | 0% |
| Sunday Night | 35°F | Mostly Cloudy | 1 mph NNW | 1% |
| Monday | 60°F | Patchy Fog then Partly Sunny | 1 mph NE | 2% |
| Monday Night | 35°F | Mostly Cloudy | 0 mph | 6% |
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 Nov 4, 2026.