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

Heavy Rain and Flooding Concerns in Hawaii; Severe Weather in the Plains

A storm system is expected to bring strong winds, widespread heavy rainfall, and flooding concerns to the Hawaiian Islands through the weekend. Strong to severe thunderstorms are forecast from the Southern Plains to the Mid-Missouri Valley this afternoon and evening. Large hail and strong winds are the primary threats. Read More >

Current conditions at

LOS ALTOS (LOAC1)

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

NA

74°F

23°C

Humidity 49%
Wind Speed WNW 6 MPH
Barometer NA
Dewpoint 54°F (12°C)
Visibility NA
Last update 09 Apr 03:10 PM PDT
Extended Forecast for

Portola Valley CA

  • Tonight

    Tonight: Showers likely, mainly after 5am. Mostly cloudy, with a low around 52. West southwest wind around 5 mph becoming calm in the evening. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

    Low: 52 °F

    Slight Chance
    Showers then
    Showers
    Likely

  • Friday

    Friday: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 8am. Mostly cloudy, with a high near 68. Calm wind becoming south southwest 5 to 9 mph in the morning. Winds could gust as high as 18 mph. Chance of precipitation is 70%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

    High: 68 °F

    Showers
    Likely

  • Friday Night

    Friday Night: A chance of showers and thunderstorms, then showers likely after 11pm. Mostly cloudy, with a low around 50. South southwest wind 3 to 8 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    Low: 50 °F

    Showers
    Likely

  • Saturday

    Saturday: Showers, with thunderstorms also possible after 2pm. High near 63. Light south wind increasing to 9 to 14 mph in the morning. Winds could gust as high as 29 mph. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.

    High: 63 °F

    Showers

  • Saturday Night

    Saturday Night: Showers and possibly a thunderstorm. Low around 46. South southwest wind 7 to 14 mph, with gusts as high as 28 mph. Chance of precipitation is 100%. New rainfall amounts between a quarter and half of an inch possible.

    Low: 46 °F

    Showers

  • Sunday

    Sunday: Showers, with thunderstorms also possible after 11am. High near 61. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    High: 61 °F

    Showers

  • Sunday Night

    Sunday Night: A 40 percent chance of rain. Mostly cloudy, with a low around 45.

    Low: 45 °F

    Chance Rain

  • Monday

    Monday: Mostly sunny, with a high near 66.

    High: 66 °F

    Mostly Sunny

  • Monday Night

    Monday Night: Mostly clear, with a low around 46.

    Low: 46 °F

    Mostly Clear

Detailed Forecast

Tonight
Showers likely, mainly after 5am. Mostly cloudy, with a low around 52. West southwest wind around 5 mph becoming calm in the evening. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.
Friday
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 8am. Mostly cloudy, with a high near 68. Calm wind becoming south southwest 5 to 9 mph in the morning. Winds could gust as high as 18 mph. Chance of precipitation is 70%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Friday Night
A chance of showers and thunderstorms, then showers likely after 11pm. Mostly cloudy, with a low around 50. South southwest wind 3 to 8 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Saturday
Showers, with thunderstorms also possible after 2pm. High near 63. Light south wind increasing to 9 to 14 mph in the morning. Winds could gust as high as 29 mph. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.
Saturday Night
Showers and possibly a thunderstorm. Low around 46. South southwest wind 7 to 14 mph, with gusts as high as 28 mph. Chance of precipitation is 100%. New rainfall amounts between a quarter and half of an inch possible.
Sunday
Showers, with thunderstorms also possible after 11am. High near 61. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Sunday Night
A 40 percent chance of rain. Mostly cloudy, with a low around 45.
Monday
Mostly sunny, with a high near 66.
Monday Night
Mostly clear, with a low around 46.
Tuesday
Mostly sunny, with a high near 67.
Tuesday Night
Mostly clear, with a low around 45.
Wednesday
Mostly sunny, with a high near 69.
Wednesday Night
Partly cloudy, with a low around 48.
Thursday
Mostly sunny, with a high near 70.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Portola Valley CA
 37.39°N 122.23°W (Elev. 397 ft)
Last Update:
1:26 pm PDT Apr 9, 2026
Forecast Valid:
3pm PDT Apr 9, 2026-6pm PDT Apr 16, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

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