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Port Costa, CA Weather

It is 57°F and clear in Port Costa, CA, observed at 10 PM PDT. Tonight: Mostly Cloudy, low 49°F. Hourly and 10-day forecast from the National Weather Service. Times are local (PDT).

Port Costa, CA current weather

57°F

Clear

H -- / L 49°Feels like 57°

  • No rain expected in the next 12 hours

Observed at Concord, Buchanan Field (8.1 mi away), 10/30/2026, 10:00 PM PDT

Hourly forecast

NWS, updated 10/30/2026, 1:26 PM PT

  1. Now54°
  2. 11 PM53°
  3. 12 AM52°Sat
  4. 1 AM52°
  5. 2 AM51°
  6. 3 AM51°
  7. 4 AM50°
  8. 5 AM50°
  9. 6 AM50°
  10. 7 AM50°
  11. 8 AM50°
  12. 9 AM52°
  13. 10 AM55°
  14. 11 AM58°
  15. 12 PM60°
  16. 1 PM61°
  17. 2 PM61°
  18. 3 PM61°
  19. 4 PM61°
  20. 5 PM60°
  21. 6 PM57°
  22. 7 PM54°
  23. 8 PM53°
  24. 9 PM53°
  25. 10 PM52°
  26. 11 PM52°
  27. 12 AM51°11%Sun
  28. 1 AM51°24%
  29. 1 AM51°25%
  30. 2 AM50°29%
  31. 3 AM50°17%
  32. 4 AM49°
  33. 5 AM48°
  34. 6 AM48°
  35. 7 AM48°
  36. 8 AM51°
  37. 9 AM54°
  38. 10 AM58°
  39. 11 AM60°
  40. 12 PM63°
  41. 1 PM64°
  42. 2 PM65°
  43. 3 PM65°
  44. 4 PM64°
  45. 5 PM61°
  46. 6 PM57°
  47. 7 PM54°
  48. 8 PM52°

10-day forecast

Tap a day for details

  • Today10/30Low 49°High

    Tonight: Mostly cloudy, with a low around 49. Southwest wind around 6 mph.

    Mostly Cloudy
  • Sat10/3129% chance of precipitationLow 48°High 62°

    Saturday: Partly sunny. High near 62, with temperatures falling to around 60 in the afternoon. West southwest wind 6 to 9 mph.

    Saturday Night: A chance of rain showers between 1am and 4am. Partly cloudy, with a low around 48. West southwest wind around 7 mph. Chance of precipitation is 30%. New rainfall amounts less than a tenth of an inch possible.

    Partly Sunny
  • Sun11/1Low 46°High 65°

    Sunday: Sunny, with a high near 65. Northwest wind around 7 mph.

    Sunday Night: Mostly clear, with a low around 46. Northwest wind around 5 mph.

    Sunny
  • Mon11/2Low 47°High 65°

    Monday: Mostly sunny, with a high near 65.

    Monday Night: Mostly cloudy, with a low around 47.

    Mostly Sunny
  • Tue11/321% chance of precipitationLow 49°High 66°

    Tuesday: A slight chance of rain between 10am and 4pm. Mostly sunny, with a high near 66.

    Tuesday Night: Mostly cloudy, with a low around 49.

    Slight Chance Light Rain
  • Wed11/418% chance of precipitationLow 49°High 66°

    Wednesday: Partly sunny, with a high near 66.

    Wednesday Night: A slight chance of rain after 4am. Partly cloudy, with a low around 49.

    Partly Sunny
  • Thu11/520% chance of precipitationLow 50°High 64°

    Thursday: A slight chance of rain. Mostly sunny, with a high near 64.

    Thursday Night: A slight chance of rain before 10pm. Partly cloudy, with a low around 50.

    Slight Chance Light Rain
  • Fri11/612% chance of precipitationLow High 66°

    Friday: Mostly sunny, with a high near 66.

    Mostly Sunny
  • Sat11/7Model blendLow 49°High 72°

    Saturday: Mostly sunny. High near 72°. Low that night near 49°.

    Computer model guidance from the NOAA National Blend of Models, not a forecast written by NWS forecasters. Expect changes this far out.

  • Sun11/8Model blendLow 50°High 71°

    Sunday: Mostly sunny. High near 71°. Low that night near 50°.

    Computer model guidance from the NOAA National Blend of Models, not a forecast written by NWS forecasters. Expect changes this far out.

Forecast for 38.045, -122.185 from the NWS MTR office, updated 10/30/2026, 1:26 PM PT · Official forecast on weather.gov

Days 9 to 10: NOAA National Blend of Models, station KCCR (Concord/Buchanan Fld, 8 mi), model run 10/30/2026, 7:00 PM PDT

From the National Weather Service; may be delayed. Not for life-safety decisions. In an emergency, call 911.

Next 6 hours

NWS hourly forecast

  1. Now54°Partly Cloudy1%6 mph
  2. 11 PM53°Partly Cloudy1%6 mph
  3. 12 AM52°Mostly Cloudy1%5 mph
  4. 1 AM52°Mostly Cloudy0%5 mph
  5. 2 AM51°Mostly Cloudy1%6 mph
  6. 3 AM51°Mostly Cloudy1%5 mph

Hourly details

Next 7 days: temperature chart, feels like, rain and snow amounts, sky cover, wind and gustsShow

Radar and satellite

National radar

NEXRAD (up to 24 hours) and GOES

Latest

Frequently asked questions

What is the weather in Port Costa, CA right now?
The latest observation from Concord, Buchanan Field was 57°F and clear, reported at 10/30/2026, 10:00 PM PDT.
Will it rain in Port Costa, CA in the next 24 hours?
The NWS hourly forecast does not show any hour with a 50% or higher chance of precipitation in the next 24 hours.
What is the 10-day forecast for Port Costa, CA?
The first 8 days come from the National Weather Service forecast. Days 9 to 10 (Nov 7 to Nov 8) come from the NOAA National Blend of Models, with highs of 71°F to 72°F. Model guidance this far out often changes.
What time is sunrise and sunset in Port Costa, CA today?
Sunrise is about 7:32 AM PDT and sunset is about 6:11 PM PDT (calculated for the center of the area, within a few minutes).
What is the normal October weather in Port Costa, CA?
At Vallejo, the 1991 to 2020 normal high in October is 79°F and the normal low is 54°F.

Rain and snow totals

Next 3 days, NWS forecast grid

Rain (liquid)
0.02 in
Snow
0.00 in
Ice
0.00 in

Nearby hazards

California hazards

Severe storm and flash flood outlooks, expected rain, river flooding and wildfires near this area

  • Severe storm outlook today:No thunderstorm risk area over this locationOutlook map
  • Excessive rainfall outlook (flash flood risk):Could not check the Weather Prediction Center outlook right now.
  • River gauges within 40 miles at or above flood stage: None reported
  • Active wildfires within 50 miles: None reported

UV and air quality forecast

EPA and AirNow

AQI forecast tomorrow (Concord)
50GoodPM2.5
AQI forecast tomorrow (Concord)
44GoodPM2.5

UV index guide · Air quality

Drought

By county

Contra Costa County, week of 10/27/2026

No drought or abnormal dryness in this county.

Tides nearby

NOAA tide stations

Beaches nearby

EPA BEACON beaches

Sun and moon

Local time, center of the area

Sunrise
7:32 AM
Sunset
6:11 PM
Daylight
10 hr 39 min
Moon
Waning Gibbous 74% lit
First light (civil dawn)
7:05 AM
Last light (civil dusk)
6:39 PM
Moonrise
10:03 PM
Moonset
12:47 PM

Normal October weather

Climate

Normal October high 79°, low 54°, precipitation 1.02 in for the month. 1991 to 2020 normals at Vallejo, 4 mi away.

Other places nearby

Data sources

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About this data

Weather and emergencies: Weather, air quality and hazard information on this page is delayed and may be incomplete. It is not a substitute for official warnings. Always follow the National Weather Service, local emergency management and public safety officials. In an emergency, call 911. For evacuation orders, use your local official alert system.

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