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Port Costa, CA Marine Weather Forecast

Today - 58°F
Dec 05, 2025
7 mph ESE
Sunny
Sunny. High near 58, with temperatures falling to around 54 in the afternoon. East southeast wind around 7 mph.
Tonight - 43°F
Dec 05, 2025
3 to 9 mph SE
Partly Cloudy
Partly cloudy, with a low around 43. Southeast wind 3 to 9 mph.
Saturday - 59°F
Dec 06, 2025
5 to 9 mph E
Mostly Sunny
Mostly sunny. High near 59, with temperatures falling to around 57 in the afternoon. East wind 5 to 9 mph.
Saturday Night - 45°F
Dec 06, 2025
2 to 7 mph E
Partly Cloudy
Partly cloudy, with a low around 45. East wind 2 to 7 mph.
Sunday - 62°F
Dec 07, 2025
5 mph NW
Patchy Fog then Partly Sunny
Patchy fog between 7am and 10am. Partly sunny, with a high near 62. Northwest wind around 5 mph.
Sunday Night - 46°F
Dec 07, 2025
3 to 8 mph SSE
Partly Cloudy
Partly cloudy, with a low around 46.
Monday - 62°F
Dec 08, 2025
2 to 7 mph NNE
Mostly Sunny
Mostly sunny, with a high near 62.
Monday Night - 47°F
Dec 08, 2025
2 mph W
Partly Cloudy then Patchy Fog
Patchy fog after 3am. Partly cloudy, with a low around 47.
Tuesday - 62°F
Dec 09, 2025
5 mph NW
Patchy Fog then Partly Sunny
Patchy fog before 7am. Partly sunny, with a high near 62.
Tuesday Night - 48°F
Dec 09, 2025
2 mph W
Partly Cloudy then Patchy Fog
Patchy fog between midnight and 4am. Partly cloudy, with a low around 48.
Wednesday - 64°F
Dec 10, 2025
5 mph NW
Mostly Sunny
Mostly sunny, with a high near 64.
Wednesday Night - 49°F
Dec 10, 2025
2 mph W
Patchy Fog
Patchy fog between 9pm and 1am. Mostly clear, with a low around 49.
Thursday - 64°F
Dec 11, 2025
2 to 6 mph N
Mostly Sunny
Mostly sunny, with a high near 64.
Thursday Night - 48°F
Dec 11, 2025
3 mph NNW
Patchy Fog
Patchy fog between 9pm and 1am. Mostly clear, with a low around 48.

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