Ontario, OR Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Ontario, a city in Payette County, Oregon.
Overnight
55°F
Smoke
Smoke. Mostly clear. Low around 55, with temperatures rising to around 59 overnight. West wind around 3 mph.
7-day forecast for Ontario
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 55°F | Smoke | 3 mph W | 0% |
| Tuesday | 91°F | Smoke | 3 mph W | 0% |
| Tuesday Night | 58°F | Smoke | 2 mph SW | 0% |
| Wednesday | 95°F | Smoke | 2 mph SSE | 0% |
| Wednesday Night | 60°F | Areas Of Smoke | 1 mph SSE | 0% |
| Thursday | 101°F | Areas Of Smoke | 1 mph SE | 0% |
| Thursday Night | 65°F | Areas Of Smoke | 2 mph S | 0% |
| Friday | 102°F | Sunny | 2 mph WNW | 0% |
| Friday Night | 68°F | Mostly Clear | 5 to 9 mph NW | 0% |
| Saturday | 101°F | Sunny | 6 mph NW | 0% |
| Saturday Night | 67°F | Mostly Clear | 5 to 9 mph NW | 0% |
| Sunday | 97°F | Sunny | 8 mph NW | 0% |
| Sunday Night | 65°F | Mostly Clear | 5 to 10 mph NNW | 0% |
| Monday | 96°F | Sunny | 7 mph NW | 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 Aug 4, 2026.