National Weather Service Forecast for: Diamond Bar CA
Issued by: National Weather Service Los Angeles/Oxnard, CA
Updated: 1:21 pm PST Dec 22, 2025
 
This
Afternoon
This Afternoon: Partly sunny, with a high near 70. West southwest wind around 5 mph.
Partly Sunny

 Tonight

Tonight: Mostly cloudy, with a low around 52. South southwest wind around 5 mph becoming calm.
Mostly Cloudy

 Tuesday

Tuesday: Rain, mainly after 4pm. High near 65. South southeast wind 5 to 10 mph, with gusts as high as 15 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.
Slight Chance
Rain then
Rain
 Tuesday
Night
Tuesday Night: Rain before 10pm, then rain and possibly a thunderstorm between 10pm and 1am, then showers and possibly a thunderstorm after 1am. Low around 55. Southeast wind around 15 mph, with gusts as high as 25 mph. Chance of precipitation is 100%. New rainfall amounts between 1 and 2 inches possible.
Showers

 Wednesday

Wednesday: Showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. High near 62. South wind around 15 mph, with gusts as high as 25 mph. Chance of precipitation is 100%. New rainfall amounts between 2 and 3 inches possible.
Heavy Rain

 Wednesday
Night
Wednesday Night: Showers. Low around 53. Chance of precipitation is 100%.
Showers

 Christmas
Day
Christmas Day: Showers. High near 62. Chance of precipitation is 90%.
Showers

 Thursday
Night
Thursday Night: Showers. Cloudy, with a low around 52.
Showers

 Friday

Friday: Showers. Mostly cloudy, with a high near 60.
Showers
Hi 70 °F Lo 52 °F Hi 65 °F Lo 55 °F Hi 62 °F Lo 53 °F Hi 62 °F Lo 52 °F Hi 60 °F

Flood Watch
 

This Afternoon
 
 Partly sunny, with a high near 70. West southwest wind around 5 mph.
Tonight
 
 Mostly cloudy, with a low around 52. South southwest wind around 5 mph becoming calm.
Tuesday
 
 Rain, mainly after 4pm. High near 65. South southeast wind 5 to 10 mph, with gusts as high as 15 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.
Tuesday Night
 
 Rain before 10pm, then rain and possibly a thunderstorm between 10pm and 1am, then showers and possibly a thunderstorm after 1am. Low around 55. Southeast wind around 15 mph, with gusts as high as 25 mph. Chance of precipitation is 100%. New rainfall amounts between 1 and 2 inches possible.
Wednesday
 
 Showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. High near 62. South wind around 15 mph, with gusts as high as 25 mph. Chance of precipitation is 100%. New rainfall amounts between 2 and 3 inches possible.
Wednesday Night
 
 Showers. Low around 53. Chance of precipitation is 100%.
Christmas Day
 
 Showers. High near 62. Chance of precipitation is 90%.
Thursday Night
 
 Showers. Cloudy, with a low around 52.
Friday
 
 Showers. Mostly cloudy, with a high near 60.
Friday Night
 
 A chance of showers. Mostly cloudy, with a low around 44.
Saturday
 
 A slight chance of showers. Mostly sunny, with a high near 60.
Saturday Night
 
 A slight chance of showers. Mostly clear, with a low around 43.
Sunday
 
 Sunny, with a high near 63.

 

Forecast from NOAA-NWS for Diamond Bar CA.