National Weather Service Forecast for: Ontario International Arpt CA
Issued by: National Weather Service San Diego, CA
Updated: 12:18 am PDT Sep 13, 2026
 
Overnight

Overnight: Partly cloudy, with a low around 68. Calm wind becoming west around 5 mph.
Partly Cloudy
 Sunday

Sunday: Patchy fog before 11am. Otherwise, sunny, with a high near 90. Light and variable wind becoming west 5 to 10 mph in the afternoon. Winds could gust as high as 20 mph.
Patchy Fog
then Sunny
 Sunday
Night
Sunday Night: Mostly clear, with a low around 66. West wind 5 to 10 mph becoming light and variable in the evening.
Mostly Clear
 Monday

Monday: Sunny, with a high near 90. Light and variable wind becoming west 5 to 10 mph in the afternoon. Winds could gust as high as 20 mph.
Sunny
 Monday
Night
Monday Night: Mostly clear, with a low around 64. West wind 5 to 10 mph, with gusts as high as 20 mph.
Mostly Clear
 Tuesday

Tuesday: Sunny, with a high near 89.
Sunny
 Tuesday
Night
Tuesday Night: Mostly clear, with a low around 62.
Mostly Clear
 Wednesday

Wednesday: Sunny, with a high near 91.
Sunny
 Wednesday
Night
Wednesday Night: Clear, with a low around 62.
Clear
Lo 68 °F Hi 90 °F Lo 66 °F Hi 90 °F Lo 64 °F Hi 89 °F Lo 62 °F Hi 91 °F Lo 62 °F

 

Overnight
 
 Partly cloudy, with a low around 68. Calm wind becoming west around 5 mph.
Sunday
 
 Patchy fog before 11am. Otherwise, sunny, with a high near 90. Light and variable wind becoming west 5 to 10 mph in the afternoon. Winds could gust as high as 20 mph.
Sunday Night
 
 Mostly clear, with a low around 66. West wind 5 to 10 mph becoming light and variable in the evening.
Monday
 
 Sunny, with a high near 90. Light and variable wind becoming west 5 to 10 mph in the afternoon. Winds could gust as high as 20 mph.
Monday Night
 
 Mostly clear, with a low around 64. West wind 5 to 10 mph, with gusts as high as 20 mph.
Tuesday
 
 Sunny, with a high near 89.
Tuesday Night
 
 Mostly clear, with a low around 62.
Wednesday
 
 Sunny, with a high near 91.
Wednesday Night
 
 Clear, with a low around 62.
Thursday
 
 Sunny, with a high near 90.
Thursday Night
 
 Clear, with a low around 65.
Friday
 
 Sunny, with a high near 95.
Friday Night
 
 Clear, with a low around 68.
Saturday
 
 Sunny, with a high near 97.

 

Forecast from NOAA-NWS for Ontario International Arpt CA.