National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce

Heavy Rain and Mountain Snow Lingers in California; Winter Storm Impacting the Great Lakes and Northeast U.S.

An atmospheric river will wind down through today across California with lingering heavy rainfall, heavy mountain snow, and gusty winds. A wintry mix of freezing rain, sleet, and snow will cause hazardous travel conditions for the Great Lakes into the northern Mid-Atlantic and southern New England today through Saturday morning. Areas of tree damage and power outages are possible. Read More >

Hazardous Weather Conditions

Current conditions at

LOS ALTOS (LOAC1)

Lat: 37.35472°NLon: 122.14167°WElev: 539.0ft.

NA

52°F

11°C

Humidity 75%
Wind Speed S 4 MPH
Barometer NA
Dewpoint 44°F (7°C)
Visibility NA
Last update 26 Dec 06:10 AM PST
Extended Forecast for

2 Miles NNW Portola Valley CA

Flood Watch December 26, 06:44am until December 26, 10:00pm
Click here for hazard details and duration
Flood Watch
  •  
    Flood Watch December 26, 06:44am until December 26, 10:00pm

    NOW until 10:00pm Fri

    Flood Watch

  • Today

    High: 57 °F

    Chance
    Showers

  • Tonight

    Tonight: A 40 percent chance of showers, mainly before 1am. Mostly cloudy, with a low around 44. West southwest wind around 6 mph. New precipitation amounts of less than a tenth of an inch possible.

    Low: 44 °F

    Chance
    Showers

  • Saturday

    Saturday: Mostly sunny, with a high near 55. North wind around 7 mph.

    High: 55 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Increasing clouds, with a low around 38. Light north northeast wind.

    Low: 38 °F

    Increasing
    Clouds

  • Sunday

    Sunday: Sunny, with a high near 55. Calm wind becoming north northeast around 6 mph in the morning.

    High: 55 °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 58.

    High: 58 °F

    Sunny

  • Monday Night

    Monday Night: Clear, with a low around 38.

    Low: 38 °F

    Clear

Detailed Forecast

Today
A 50 percent chance of showers, mainly between 7am and 5pm. Partly sunny, with a high near 57. South southwest wind 10 to 16 mph, with gusts as high as 28 mph. New precipitation amounts between a tenth and quarter of an inch possible.
Tonight
A 40 percent chance of showers, mainly before 1am. Mostly cloudy, with a low around 44. West southwest wind around 6 mph. New precipitation amounts of less than a tenth of an inch possible.
Saturday
Mostly sunny, with a high near 55. North wind around 7 mph.
Saturday Night
Increasing clouds, with a low around 38. Light north northeast wind.
Sunday
Sunny, with a high near 55. Calm wind becoming north northeast around 6 mph in the morning.
Sunday Night
Mostly clear, with a low around 37.
Monday
Sunny, with a high near 58.
Monday Night
Clear, with a low around 38.
Tuesday
Sunny, with a high near 60.
Tuesday Night
Mostly clear, with a low around 40.
Wednesday
Mostly sunny, with a high near 59.
Wednesday Night
A slight chance of showers. Mostly cloudy, with a low around 43.
New Year's Day
A chance of showers. Mostly cloudy, with a high near 58.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
2 Miles NNW Portola Valley CA
 37.42°N 122.23°W (Elev. 397 ft)
Last Update:
3:07 am PST Dec 26, 2025
Forecast Valid:
6am PST Dec 26, 2025-6pm PST Jan 1, 2026
 
Forecast Discussion
 
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Additional Resources

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Hourly Weather Forecast

National Digital Forecast Database

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation