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

Prolonged Atmospheric River Will Impact the Northwest Early this Week

A weather system in the Pacific Northwest will produce rain throughout the day, before a potent atmospheric river produces a prolonged round of heavy rainfall, widespread urban and river flooding, and high elevation snow to the region Monday through Wednesday. Showers and thunderstorms may produce isolated damaging winds, a brief tornado, and locally heavy rainfall across parts of Florida today. Read More >

Current conditions at

SJSU - Mount Diablo Summit Museum Rooftop (SJS02)

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

NA

56°F

13°C

Humidity 34%
Wind Speed NW 12 MPH
Barometer NA
Dewpoint 28°F (-2°C)
Visibility NA
Last update 07 Dec 06:05 PM PST
Extended Forecast for

3 Miles NNE San Ramon CA

  • Tonight

    Tonight: Patchy dense fog after 7pm. Otherwise, mostly clear, with a low around 40. Calm wind.

    Low: 40 °F

    Patchy Dense
    Fog

  • Monday

    Monday: Widespread dense fog, mainly before 9am. Otherwise, sunny, with a high near 62. Calm wind.

    High: 62 °F

    Dense Fog
    then Sunny

  • Monday Night

    Monday Night: Patchy fog. Otherwise, mostly clear, with a low around 41. Calm wind.

    Low: 41 °F

    Patchy Fog

  • Tuesday

    Tuesday: Widespread fog, mainly before 7am. Otherwise, sunny, with a high near 62. Calm wind.

    High: 62 °F

    Fog then
    Sunny

  • Tuesday Night

    Tuesday Night: Patchy fog. Otherwise, mostly clear, with a low around 42. Calm wind.

    Low: 42 °F

    Patchy Fog

  • Wednesday

    Wednesday: Areas of fog before 10am. Otherwise, sunny, with a high near 65.

    High: 65 °F

    Areas Fog
    then Sunny

  • Wednesday Night

    Wednesday Night: Patchy fog. Otherwise, mostly clear, with a low around 43.

    Low: 43 °F

    Patchy Fog

  • Thursday

    Thursday: Widespread fog, mainly before 8am. Otherwise, sunny, with a high near 64.

    High: 64 °F

    Fog then
    Sunny

  • Thursday Night

    Thursday Night: Patchy fog after 2am. Otherwise, mostly clear, with a low around 42.

    Low: 42 °F

    Mostly Clear
    then Patchy
    Fog

Detailed Forecast

Tonight
Patchy dense fog after 7pm. Otherwise, mostly clear, with a low around 40. Calm wind.
Monday
Widespread dense fog, mainly before 9am. Otherwise, sunny, with a high near 62. Calm wind.
Monday Night
Patchy fog. Otherwise, mostly clear, with a low around 41. Calm wind.
Tuesday
Widespread fog, mainly before 7am. Otherwise, sunny, with a high near 62. Calm wind.
Tuesday Night
Patchy fog. Otherwise, mostly clear, with a low around 42. Calm wind.
Wednesday
Areas of fog before 10am. Otherwise, sunny, with a high near 65.
Wednesday Night
Patchy fog. Otherwise, mostly clear, with a low around 43.
Thursday
Widespread fog, mainly before 8am. Otherwise, sunny, with a high near 64.
Thursday Night
Patchy fog after 2am. Otherwise, mostly clear, with a low around 42.
Friday
Areas of fog before 11am. Otherwise, sunny, with a high near 63.
Friday Night
Patchy fog. Otherwise, mostly clear, with a low around 41.
Saturday
Areas of fog. Otherwise, mostly sunny, with a high near 64.
Saturday Night
Patchy fog. Otherwise, partly cloudy, with a low around 42.
Sunday
Areas of fog. Otherwise, mostly sunny, with a high near 62.
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ABOUT THIS FORECAST

 
Point Forecast:
3 Miles NNE San Ramon CA
 37.8°N 121.93°W (Elev. 640 ft)
Last Update:
5:02 pm PST Dec 7, 2025
Forecast Valid:
6pm PST Dec 7, 2025-6pm PST Dec 14, 2025
 
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Additional Resources

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National Digital Forecast Database

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Chance of Precipitation