California · NWS LOX office

Diamond Bar, CA weather

It is 59°F at WHITTIER HILLS as of Oct 28, 1:57 AM PDT. Overnight: Patchy Fog, low near 55°F. Forecast from the National Weather Service, issued Oct 28, 1:41 AM PDT.

Updated Oct 28, 2:20 AM PDT (snapshot)

Current conditions

Temperature

59°F

Patchy Fog

Wind

ESE 6 mph, gusts 8 mph

Humidity 100% · dew point 59°F

Pressure · visibility

—

Visibility —

Observed at WHITTIER HILLS (WTHC1), Oct 28, 1:57 AM PDT. Station readings can lag or be missing.

Alerts for this area

No active NWS alerts cover the Diamond Bar forecast zone right now.

Around the NWS LOX forecast area

1 active alert covers zones served by the LOX office near Diamond Bar:

  • Coastal Flood Advisory

From the alert snapshot of Oct 28, 2026, 5:12 AM EDT. California has 8 active alerts: see them all.

For official warnings, check weather.gov and your local authorities. OpenForecast repeats National Weather Service alerts and may be delayed or incomplete. Follow instructions from emergency officials.

Next 24 hours

Hourly forecast for Diamond Bar (local time)
TimeTempForecastPrecip. chanceWind
Wed 2 AM57°FPatchy Fog0%SE 5 mph
Wed 3 AM57°FPatchy Fog0%SE 5 mph
Wed 4 AM57°FPatchy Fog0%SE 5 mph
Wed 5 AM55°FPatchy Fog1%NE 5 mph
Wed 6 AM55°FPatchy Fog1%NE 5 mph
Wed 7 AM55°FPatchy Fog1%NE 5 mph
Wed 8 AM57°FPatchy Fog1% 0 mph
Wed 9 AM61°FPatchy Fog1% 0 mph
Wed 10 AM64°FPatchy Fog1% 0 mph
Wed 11 AM68°FMostly Sunny0% 0 mph
Wed 12 PM72°FMostly Sunny0% 0 mph
Wed 1 PM75°FMostly Sunny0% 0 mph
Wed 2 PM75°FMostly Sunny0%SW 5 mph
Wed 3 PM77°FMostly Sunny0%SW 5 mph
Wed 4 PM74°FMostly Sunny0%SW 5 mph
Wed 5 PM71°FMostly Sunny0%SW 5 mph
Wed 6 PM67°FPartly Cloudy0%SW 5 mph
Wed 7 PM64°FPartly Cloudy0%SW 5 mph
Wed 8 PM62°FPartly Cloudy0%WSW 5 mph
Wed 9 PM62°FPartly Cloudy0%WSW 5 mph
Wed 10 PM61°FPartly Cloudy0%WSW 5 mph
Wed 11 PM59°FMostly Cloudy0% 0 mph
Thu 12 AM59°FMostly Cloudy0% 0 mph
Thu 1 AM59°FMostly Cloudy0% 0 mph

Hourly values come from the NWS gridded forecast for the 2.5 km grid square that covers the city's center point. Conditions elsewhere in Diamond Bar can differ.

7-day forecast

Overnight

Low 55°F

Patchy fog after 5am. Mostly cloudy, with a low around 55. East wind around 5 mph.

Wednesday

High 74°F·Low 56°F

Patchy fog before 11am. Partly sunny, with a high near 74. South wind 0 to 5 mph.

Wednesday Night: Mostly cloudy, with a low around 56. South wind 0 to 5 mph.

Thursday

High 72°F·Low 58°F

Partly sunny, with a high near 72. South wind 0 to 10 mph.

Thursday Night: Mostly cloudy, with a low around 58. Southwest wind around 5 mph.

Friday

High 68°F·Low 55°F

Partly sunny, with a high near 68.

Friday Night: Mostly cloudy, with a low around 55.

Saturday

High 67°F·Low 56°F

A chance of rain showers after 11am. Mostly cloudy, with a high near 67.

Saturday Night: Rain showers likely. Cloudy, with a low around 56.

Sunday

High 69°F·Low 53°F

A chance of rain showers before 4pm. Partly sunny, with a high near 69.

Sunday Night: Mostly clear, with a low around 53.

Monday

High 73°F·Low 55°F

Sunny, with a high near 73.

Monday Night: Mostly clear, with a low around 55.

Tuesday

High 73°F

Mostly sunny, with a high near 73.

Nearby cities

Larger cities in the area

Other cities in Los Angeles County

See every city we cover in California, or check all active alerts.

About this forecast

Forecast office
Diamond Bar is served by the National Weather Service LOX forecast office, forecast zone CAZ548, county zone CAC037.
Location used
The Census Bureau's internal point for Diamond Bar (34.0016, -117.8176), in Los Angeles County. Population: 52,292 (2024 estimate), number 173 of the 296 California cities on this site.
Radar
Nearest NWS radar: KSOX. View it on radar.weather.gov.

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Sources

  • Forecast, hourly forecast, observations and alerts: National Weather Service API, api.weather.gov/points/34.0016,-117.8176 (forecast issued Oct 28, 1:41 AM PDT).
  • Official forecast page: forecast.weather.gov.
  • City location and population: U.S. Census Bureau, Vintage 2024 population estimates and 2024 Gazetteer files.
  • Snapshot taken Oct 28, 2026. The NWS and Census Bureau do not endorse OpenForecast.

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