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

Lake Effect Snow through Friday; Heavy Rain, Thunderstorms and Mountain Snow in California

Periods of moderate to heavy lake effect snow will continue through Friday downwind of Lake Erie and Ontario. Several additional inches of accumulating snow are expected. A Pacific storm will bring heavy rain and mountain snow across California, the Southwest and Intermountain West today. Isolated severe thunderstorms and scattered flash flooding is possible across parts of southern California. Read More >

Hazardous Weather Conditions

Current conditions at

SJSU - Mount Diablo Summit Museum Rooftop (SJS02)

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

NA

45°F

7°C

Humidity 100%
Wind Speed S 15 MPH
Barometer NA
Dewpoint 45°F (7°C)
Visibility NA
Wind Chill38°F (3°C)
Last update 01 Jan 04:20 PM PST
Extended Forecast for

3 Miles SSE Clayton CA

Wind Advisory January 2, 01:00pm until January 3, 01:00pm
Click here for hazard details and duration
Wind Advisory

  • New Year's Day

    New Year's Day: A 20 percent chance of rain. Mostly cloudy, with a high near 53. South wind 16 to 18 mph, with gusts as high as 28 mph. New precipitation amounts of less than a tenth of an inch possible.

    High: 53 °F

    Slight Chance
    Rain

  • Tonight

    Tonight: A 30 percent chance of rain, mainly before 10pm. Mostly cloudy, with a steady temperature around 50. South wind 9 to 18 mph, with gusts as high as 28 mph. New precipitation amounts of less than a tenth of an inch possible.

    Low: 50 °F

    Chance Rain
    then Mostly
    Cloudy

  • Friday

    Friday: Rain likely after 4pm. Mostly cloudy, with a high near 54. South southeast wind 11 to 16 mph, with gusts as high as 24 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

    High: 54 °F

    Partly Sunny
    then Rain
    Likely

  • Friday Night

    Friday Night: Rain. Low around 50. Breezy, with a south southeast wind 18 to 23 mph, with gusts as high as 40 mph. Chance of precipitation is 100%. New precipitation amounts between a quarter and half of an inch possible.

    Low: 50 °F

    Rain and
    Breezy

  • Saturday

    Saturday: Rain before 1pm, then showers and possibly a thunderstorm after 1pm. High near 54. Breezy, with a south wind 21 to 25 mph, with gusts as high as 37 mph. Chance of precipitation is 90%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    High: 54 °F

    Showers and
    Breezy

  • Saturday Night

    Saturday Night: Showers and possibly a thunderstorm before 7pm, then rain after 7pm. Low around 50. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    Low: 50 °F

    Showers

  • Sunday

    Sunday: Rain. High near 53. Chance of precipitation is 100%.

    High: 53 °F

    Rain

  • Sunday Night

    Sunday Night: Rain. Mostly cloudy, with a low around 46.

    Low: 46 °F

    Rain

  • Monday

    Monday: Rain likely. Mostly cloudy, with a high near 49.

    High: 49 °F

    Rain Likely

Detailed Forecast

New Year's Day
A 20 percent chance of rain. Mostly cloudy, with a high near 53. South wind 16 to 18 mph, with gusts as high as 28 mph. New precipitation amounts of less than a tenth of an inch possible.
Tonight
A 30 percent chance of rain, mainly before 10pm. Mostly cloudy, with a steady temperature around 50. South wind 9 to 18 mph, with gusts as high as 28 mph. New precipitation amounts of less than a tenth of an inch possible.
Friday
Rain likely after 4pm. Mostly cloudy, with a high near 54. South southeast wind 11 to 16 mph, with gusts as high as 24 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.
Friday Night
Rain. Low around 50. Breezy, with a south southeast wind 18 to 23 mph, with gusts as high as 40 mph. Chance of precipitation is 100%. New precipitation amounts between a quarter and half of an inch possible.
Saturday
Rain before 1pm, then showers and possibly a thunderstorm after 1pm. High near 54. Breezy, with a south wind 21 to 25 mph, with gusts as high as 37 mph. Chance of precipitation is 90%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Saturday Night
Showers and possibly a thunderstorm before 7pm, then rain after 7pm. Low around 50. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Sunday
Rain. High near 53. Chance of precipitation is 100%.
Sunday Night
Rain. Mostly cloudy, with a low around 46.
Monday
Rain likely. Mostly cloudy, with a high near 49.
Monday Night
A chance of rain, mainly before 4am. Mostly cloudy, with a low around 43.
Tuesday
A slight chance of rain. Partly sunny, with a high near 49.
Tuesday Night
A chance of rain. Mostly cloudy, with a low around 43.
Wednesday
A chance of rain. Partly sunny, with a high near 49.
Wednesday Night
A chance of rain. Mostly cloudy, with a low around 40.
Thursday
A slight chance of rain. Mostly sunny, with a high near 47.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
3 Miles SSE Clayton CA
 37.9°N 121.9°W (Elev. 1814 ft)
Last Update:
12:32 pm PST Jan 1, 2026
Forecast Valid:
4pm PST Jan 1, 2026-6pm PST Jan 8, 2026
 
Forecast Discussion
 
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Additional Resources

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Chance of Precipitation