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

48°F

9°C

Humidity 100%
Wind Speed SSE 13 MPH
Barometer NA
Dewpoint 48°F (9°C)
Visibility NA
Wind Chill43°F (6°C)
Last update 01 Jan 05:20 AM PST
Extended Forecast for

4 Miles SSE Clayton CA

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

  • Overnight

    Overnight: Showers. Steady temperature around 50. Southeast wind around 10 mph, with gusts as high as 23 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

    Low: 50 °F

    Showers

  • New Year's Day

    New Year's Day: Showers. High near 53. South southwest wind 10 to 16 mph, with gusts as high as 23 mph. Chance of precipitation is 80%. New precipitation amounts between a half and three quarters of an inch possible.

    High: 53 °F

    Showers

  • Thursday Night

    Thursday Night: Showers likely, mainly before 10pm. Mostly cloudy, with a low around 47. South wind 10 to 16 mph, with gusts as high as 23 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

    Low: 47 °F

    Showers
    Likely then
    Slight Chance
    Showers

  • Friday

    Friday: Showers likely, mainly after 4pm. Mostly cloudy, with a high near 53. South southeast wind 9 to 14 mph, with gusts as high as 22 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

    High: 53 °F

    Slight Chance
    Showers then
    Showers
    Likely

  • Friday Night

    Friday Night: Showers. Low around 52. Breezy, with a south southeast wind 18 to 23 mph, with gusts as high as 39 mph. Chance of precipitation is 100%. New precipitation amounts between a quarter and half of an inch possible.

    Low: 52 °F

    Showers and
    Breezy

  • Saturday

    Saturday: Showers. High near 55. Breezy. Chance of precipitation is 100%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 55 °F

    Showers and
    Breezy

  • Saturday Night

    Saturday Night: Showers and possibly a thunderstorm. Low around 51. Chance of precipitation is 90%.

    Low: 51 °F

    Showers

  • Sunday

    Sunday: Showers. Cloudy, with a high near 53.

    High: 53 °F

    Showers

  • Sunday Night

    Sunday Night: Showers. Cloudy, with a low around 48.

    Low: 48 °F

    Showers

Detailed Forecast

Overnight
Showers. Steady temperature around 50. Southeast wind around 10 mph, with gusts as high as 23 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.
New Year's Day
Showers. High near 53. South southwest wind 10 to 16 mph, with gusts as high as 23 mph. Chance of precipitation is 80%. New precipitation amounts between a half and three quarters of an inch possible.
Thursday Night
Showers likely, mainly before 10pm. Mostly cloudy, with a low around 47. South wind 10 to 16 mph, with gusts as high as 23 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.
Friday
Showers likely, mainly after 4pm. Mostly cloudy, with a high near 53. South southeast wind 9 to 14 mph, with gusts as high as 22 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.
Friday Night
Showers. Low around 52. Breezy, with a south southeast wind 18 to 23 mph, with gusts as high as 39 mph. Chance of precipitation is 100%. New precipitation amounts between a quarter and half of an inch possible.
Saturday
Showers. High near 55. Breezy. Chance of precipitation is 100%. New precipitation amounts between a tenth and quarter of an inch possible.
Saturday Night
Showers and possibly a thunderstorm. Low around 51. Chance of precipitation is 90%.
Sunday
Showers. Cloudy, with a high near 53.
Sunday Night
Showers. Cloudy, with a low around 48.
Monday
Showers. Mostly cloudy, with a high near 50.
Monday Night
Showers likely. Mostly cloudy, with a low around 45.
Tuesday
A chance of showers. Partly sunny, with a high near 49.
Tuesday Night
A slight chance of showers. Mostly cloudy, with a low around 42.
Wednesday
A slight chance of showers. Partly sunny, with a high near 49.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
4 Miles SSE Clayton CA
 37.9°N 121.9°W (Elev. 1814 ft)
Last Update:
1:25 am PST Jan 1, 2026
Forecast Valid:
5am PST Jan 1, 2026-6pm PST Jan 7, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

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Hourly Weather Forecast

National Digital Forecast Database

National Digital Forecast Database Maximum Temperature Forecast

High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation