Atmospheric River Bringing Heavy Rain to Southern California and Heavy Snow to the Sierra Nevadas

A strong atmospheric river will continue heavy rain over southern California through Friday. The heaviest rainfall is ongoing today in the Los Angeles Basin. Flash and urban flooding is possible. A prolonged heavy snowfall has begun over the Sierra Nevada Mountains and will continue through Friday. Travel will become increasingly difficult over the passes due to snow and strong winds. Read More >

Current conditions at

SJSU - Mount Diablo Summit Museum Rooftop (SJS02)

Lat: 37.881699°NLon: 121.914173°WElev: 3904.0ft.

NA

39°F

4°C

Humidity 100%
Wind Speed SSW 14 MPH
Barometer NA
Dewpoint 39°F (4°C)
Visibility NA
Wind Chill31°F (-1°C)
Last update 26 Dec 12:50 AM PST
Extended Forecast for

4 Miles SSE Clayton CA

Flood Watch December 26, 01:01am until December 26, 10:00pm
Click here for hazard details and duration
Flood Watch
  •  
    Flood Watch December 26, 01:01am until December 26, 10:00pm

    NOW until 10:00pm Fri

    Flood Watch

  • Overnight

    Low: 44 °F

    Chance
    Showers

  • Friday

    Friday: Showers likely, with thunderstorms also possible after 4pm.  Mostly cloudy, with a high near 49. South wind 10 to 17 mph, with gusts as high as 32 mph.  Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    High: 49 °F

    Showers
    Likely

  • Friday Night

    Friday Night: A chance of showers and thunderstorms.  Mostly cloudy, with a steady temperature around 45. South southwest wind around 9 mph.  Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

    Low: 45 °F

    Chance
    Showers

  • Saturday

    Saturday: Partly sunny, with a high near 48. North wind around 7 mph.

    High: 48 °F

    Partly Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 38. Northwest wind around 6 mph.

    Low: 38 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny, with a high near 47.

    High: 47 °F

    Sunny

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 37.

    Low: 37 °F

    Mostly Clear

  • Monday

    Monday: Sunny, with a high near 48.

    High: 48 °F

    Sunny

Detailed Forecast

Overnight
A 50 percent chance of showers. Mostly cloudy, with a low around 44. South southwest wind around 21 mph, with gusts as high as 37 mph. New precipitation amounts of less than a tenth of an inch possible.
Friday
Showers likely, with thunderstorms also possible after 4pm. Mostly cloudy, with a high near 49. South wind 10 to 17 mph, with gusts as high as 32 mph. Chance of precipitation is 60%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Friday Night
A chance of showers and thunderstorms. Mostly cloudy, with a steady temperature around 45. South southwest wind around 9 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Saturday
Partly sunny, with a high near 48. North wind around 7 mph.
Saturday Night
Mostly clear, with a low around 38. Northwest wind around 6 mph.
Sunday
Sunny, with a high near 47.
Sunday Night
Mostly clear, with a low around 37.
Monday
Sunny, with a high near 48.
Monday Night
Mostly clear, with a low around 38.
Tuesday
Mostly sunny, with a high near 50.
Tuesday Night
Mostly clear, with a low around 39.
Wednesday
Mostly sunny, with a high near 50.
Wednesday Night
A slight chance of showers. Partly cloudy, with a low around 42.
New Year's Day
A slight chance of showers. Partly sunny, with a high near 49.
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ABOUT THIS FORECAST

 
Point Forecast:
4 Miles SSE Clayton CA
 37.9°N 121.9°W (Elev. 1814 ft)
12:27 am PST Dec 26, 2025
1am PST Dec 26, 2025-6pm PST Jan 1, 2026
 
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Additional Resources

Radar & Satellite Image

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Hourly Weather Forecast

National Digital Forecast Database