Skip to content
Something wrong? Let us know

Checked

Port Costa, CA Weather

It is 55°F and clear in Port Costa, CA, observed at 2:35 AM PDT. Today: Mostly Cloudy, high 62°F, low 49°F. Hourly and 10-day forecast from the National Weather Service. Times are local (PDT).

Port Costa, CA current weather

55°F

Clear

H 62° / L 49°Feels like 55°

  • No rain expected in the next 12 hours

Observed at Concord, Buchanan Field (8.1 mi away), 10/31/2026, 2:35 AM PDT

Hourly forecast

NWS, updated 10/31/2026, 1:26 AM PT

  1. Now51°
  2. 4 AM51°
  3. 5 AM50°
  4. 6 AM50°
  5. 7 AM50°
  6. 8 AM50°
  7. 9 AM52°
  8. 10 AM56°
  9. 11 AM59°
  10. 12 PM61°
  11. 1 PM62°
  12. 2 PM62°
  13. 3 PM62°
  14. 4 PM62°
  15. 5 PM60°
  16. 6 PM57°
  17. 7 PM55°12%
  18. 8 PM54°11%
  19. 9 PM53°13%
  20. 10 PM52°18%
  21. 11 PM52°
  22. 12 AM51°18%Sun
  23. 1 AM51°35%
  24. 1 AM51°37%
  25. 2 AM50°20%
  26. 3 AM49°14%
  27. 4 AM49°
  28. 5 AM48°
  29. 6 AM48°
  30. 7 AM48°
  31. 8 AM50°
  32. 9 AM53°
  33. 10 AM56°
  34. 11 AM59°
  35. 12 PM62°
  36. 1 PM63°
  37. 2 PM63°
  38. 3 PM64°
  39. 4 PM63°
  40. 5 PM60°
  41. 6 PM56°
  42. 7 PM53°
  43. 8 PM52°
  44. 9 PM51°
  45. 10 PM51°
  46. 11 PM50°
  47. 12 AM49°Mon
  48. 1 AM48°

10-day forecast

Tap a day for details

  • Today10/31Low 49°High 62°

    Saturday: Mostly cloudy. High near 62, with temperatures falling to around 60 in the afternoon. West southwest wind 5 to 9 mph.

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

    Mostly Cloudy
  • Sun11/1Low 46°High 64°

    Sunday: Sunny, with a high near 64. West wind around 6 mph.

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

    Sunny
  • Mon11/215% chance of precipitationLow 49°High 64°

    Monday: Mostly sunny, with a high near 64.

    Monday Night: A slight chance of rain showers after 4am. Mostly cloudy, with a low around 49.

    Mostly Sunny
  • Tue11/333% chance of precipitationLow 48°High 63°

    Tuesday: A chance of rain showers before 4pm, then a slight chance of rain. Partly sunny, with a high near 63.

    Tuesday Night: A chance of rain before 4am. Mostly cloudy, with a low around 48.

    Chance Rain Showers then Slight Chance Light Rain
  • Wed11/413% chance of precipitationLow 50°High 66°

    Wednesday: Mostly sunny, with a high near 66.

    Wednesday Night: Partly cloudy, with a low around 50.

    Mostly Sunny
  • Thu11/5Low 48°High 65°

    Thursday: Mostly sunny, with a high near 65.

    Thursday Night: Partly cloudy, with a low around 48.

    Mostly Sunny
  • Fri11/6Low High 69°

    Friday: Mostly sunny, with a high near 69.

    Mostly Sunny
  • Sat11/7Model blendLow 50°High 73°

    Saturday: Mostly sunny. High near 73°. 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.

  • Sun11/8Model blendLow 51°High 72°

    Sunday: Partly cloudy. High near 72°. Low that night near 51°.

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

  • Mon11/9Model blend12% chance of precipitationLow 50°High 70°

    Monday: Partly cloudy. High near 70°. Low that night near 50°. About 0.02 in of precipitation.

    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 10/31/2026, 1:26 AM PT · Official forecast on weather.gov

Days 8 to 10: NOAA National Blend of Models, station KCCR (Concord/Buchanan Fld, 8 mi), model run 10/31/2026, 1:00 AM 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. Now51°Mostly Cloudy1%6 mph
  2. 4 AM51°Mostly Cloudy1%6 mph
  3. 5 AM50°Mostly Cloudy2%6 mph
  4. 6 AM50°Mostly Cloudy2%6 mph
  5. 7 AM50°Partly Sunny2%5 mph
  6. 8 AM50°Mostly Cloudy2%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 55°F and clear, reported at 10/31/2026, 2:35 AM PDT.
What is the high temperature today in Port Costa, CA?
The National Weather Service forecast for saturday calls for a high near 62°F. Mostly Cloudy.
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 7 days come from the National Weather Service forecast. Days 8 to 10 (Nov 7 to Nov 9) come from the NOAA National Blend of Models, with highs of 70°F to 73°F. Model guidance this far out often changes.
What time is sunrise and sunset in Port Costa, CA today?
Sunrise is about 7:33 AM PDT and sunset is about 6:10 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)
0.01 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 today (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
7:33 AM
Sunset
6:10 PM
Daylight
10 hr 37 min
Moon
Waning Gibbous 72% lit
First light (civil dawn)
7:06 AM
Last light (civil dusk)
6:37 PM
Moonrise
11:19 PM
Moonset
1:37 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

See something wrong? Request a correction

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.

Forecasts, observations and alerts come from the National Weather Service (api.weather.gov). Data can be delayed by minutes to hours, and an observation station may be miles from the place named on this page. This site is not affiliated with NOAA or the National Weather Service.

DatenUS is a private website and is not affiliated with or endorsed by any government agency. We republish public data from the sources listed on this page. Data can be incomplete, delayed or wrong. Always check the original source before you make a decision.

Our servers read this data automatically from government sources. Errors can come from the source itself or from the way we read, process or display it, and we do not guarantee that it is accurate, complete or current. Verify anything important with the official source.

Report an errorHow we check dataRead the full disclaimer