Ontario, CA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Ontario, a city in San Bernardino County, California.
Today
86°F
Sunny
Sunny, with a high near 86. Southwest wind 5 to 10 mph, with gusts as high as 20 mph.
7-day forecast for Ontario
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 86°F | Sunny | 5 to 10 mph SW | 0% |
| Tonight | 63°F | Partly Cloudy | 5 to 10 mph W | 0% |
| Sunday | 84°F | Partly Sunny | 0 to 15 mph SW | 0% |
| Sunday Night | 64°F | Mostly Cloudy | 0 to 10 mph SW | 2% |
| Monday | 81°F | Mostly Sunny | 0 to 10 mph SW | 2% |
| Monday Night | 62°F | Partly Cloudy | 0 to 10 mph W | 1% |
| Tuesday | 83°F | Sunny | 0 to 10 mph SW | 0% |
| Tuesday Night | 63°F | Clear | 0 to 10 mph W | 0% |
| Wednesday | 90°F | Sunny | 0 to 10 mph SW | 0% |
| Wednesday Night | 65°F | Mostly Clear | 0 to 10 mph W | 0% |
| Thursday | 91°F | Sunny | 0 to 10 mph W | 3% |
| Thursday Night | 66°F | Mostly Clear | 0 to 10 mph W | 4% |
| Friday | 91°F | Sunny | 0 to 5 mph W | 4% |
| Friday Night | 67°F | Mostly Clear | 0 to 5 mph W | 2% |
Forecast source: National Weather Service (api.weather.gov) for Ontario (34.038, -117.604). Updated through the day.
Growing snapshot for Ontario
Last spring frost
Jan 4
First fall frost
Dec 30
Growing season
365 days
Hardiness zone
10a
More local growing data for Ontario: nearby ZIP 91761 weather · frost dates · planting calendar · California frost dates
Nearby towns & communities
Adelanto
Apple Valley
Baker
Barstow
Big Bear City
Big Bear Lake
Big River
Bloomington
Bluewater
Chino
Chino Hills
Colton
Crestline
Fontana
Fort Irwin
Grand Terrace
Hesperia
Highland
Homestead Valley
Homewood Canyon
Joshua Tree
Lake Arrowhead
Lenwood
Loma Linda
Lucerne Valley
Lytle Creek
Mentone
Montclair
Morongo Valley
Mountain View Acres
Climate data from the nearest NOAA station, Ontario Intl Ap, Ca (1.5 mi from Ontario). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.