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

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 >

Hazardous Weather Conditions

Current conditions at

LAS TRAMPAS (LTRC1)

Lat: 37.83389°NLon: 122.06694°WElev: 1760.0ft.

NA

49°F

9°C

Humidity 100%
Wind Speed SSW 24 MPH
Barometer NA
Dewpoint 49°F (9°C)
Visibility NA
Wind Chill42°F (6°C)
Last update 24 Dec 11:28 PM PST
Extended Forecast for

2 Miles NNW San Ramon CA

Flood Watch December 25, 12:22am until December 26, 10:00pm
Wind Advisory until December 25, 10:00am
Click here for hazard details and duration
Flood Watch
Wind Advisory
  •  
    Flood Watch December 25, 12:22am until December 26, 10:00pm
    Wind Advisory until December 25, 10:00am

    NOW: Multiple hazards in effect

    Click HERE for Details

  • Overnight

    Low: 51 °F

    Severe
    Thunderstorms

  • Christmas Day

    Christmas Day: Rain and possibly a thunderstorm before 10am, then showers and possibly a thunderstorm between 10am and 4pm, then rain after 4pm. Some of the storms could be severe. High near 56. South southwest wind 16 to 20 mph, with gusts as high as 37 mph. Chance of precipitation is 90%. New rainfall amounts between a half and three quarters of an inch possible.

    High: 56 °F

    Severe
    Thunderstorms

  • Thursday Night

    Thursday Night: Rain before 7pm, then showers and possibly a thunderstorm between 7pm and 10pm, then rain likely after 10pm. Some of the storms could be severe. Low around 47. South southwest wind 14 to 17 mph, with gusts as high as 37 mph. Chance of precipitation is 100%. New precipitation amounts between a quarter and half of an inch possible.

    Low: 47 °F

    Severe
    Thunderstorms
    then Rain
    Likely

  • Friday

    Friday: Rain, mainly before 4pm. High near 54. South wind 10 to 13 mph, with gusts as high as 28 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 54 °F

    Rain

  • Friday Night

    Friday Night: A 50 percent chance of rain, mainly before 10pm. Mostly cloudy, with a low around 43. South southwest wind 3 to 6 mph. New precipitation amounts of less than a tenth of an inch possible.

    Low: 43 °F

    Chance Rain
    then Slight
    Chance Rain

  • Saturday

    Saturday: A 20 percent chance of rain before 10am. Partly sunny, with a high near 52.

    High: 52 °F

    Slight Chance
    Rain then
    Mostly Sunny

  • Saturday Night

    Saturday Night: Patchy frost after 4am. Otherwise, mostly clear, with a low around 36.

    Low: 36 °F

    Mostly Clear
    then Patchy
    Frost

  • Sunday

    Sunday: Areas of frost before 8am. Otherwise, sunny, with a high near 51.

    High: 51 °F

    Areas Frost
    then Sunny

Detailed Forecast

Overnight
Showers and possibly a thunderstorm. Some of the storms could be severe. Low around 51. South southwest wind 18 to 21 mph, with gusts as high as 49 mph. Chance of precipitation is 100%. New rainfall amounts between a quarter and half of an inch possible.
Christmas Day
Rain and possibly a thunderstorm before 10am, then showers and possibly a thunderstorm between 10am and 4pm, then rain after 4pm. Some of the storms could be severe. High near 56. South southwest wind 16 to 20 mph, with gusts as high as 37 mph. Chance of precipitation is 90%. New rainfall amounts between a half and three quarters of an inch possible.
Thursday Night
Rain before 7pm, then showers and possibly a thunderstorm between 7pm and 10pm, then rain likely after 10pm. Some of the storms could be severe. Low around 47. South southwest wind 14 to 17 mph, with gusts as high as 37 mph. Chance of precipitation is 100%. New precipitation amounts between a quarter and half of an inch possible.
Friday
Rain, mainly before 4pm. High near 54. South wind 10 to 13 mph, with gusts as high as 28 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible.
Friday Night
A 50 percent chance of rain, mainly before 10pm. Mostly cloudy, with a low around 43. South southwest wind 3 to 6 mph. New precipitation amounts of less than a tenth of an inch possible.
Saturday
A 20 percent chance of rain before 10am. Partly sunny, with a high near 52.
Saturday Night
Patchy frost after 4am. Otherwise, mostly clear, with a low around 36.
Sunday
Areas of frost before 8am. Otherwise, sunny, with a high near 51.
Sunday Night
Patchy frost after 1am. Otherwise, mostly clear, with a low around 34.
Monday
Areas of frost before 9am. Otherwise, sunny, with a high near 53.
Monday Night
Patchy frost. Otherwise, mostly clear, with a low around 34.
Tuesday
Areas of frost. Otherwise, mostly sunny, with a high near 54.
Tuesday Night
Patchy fog. Otherwise, partly cloudy, with a low around 37.
Wednesday
Mostly cloudy, with a high near 55.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
2 Miles NNW San Ramon CA
 37.77°N 121.98°W (Elev. 518 ft)
Last Update:
11:27 pm PST Dec 24, 2025
Forecast Valid:
12am PST Dec 25, 2025-6pm PST Dec 31, 2025
 
Forecast Discussion
 
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Additional Resources

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Chance of Precipitation