China Beach

Faces NW · Small Cove · Sheltered · GGNRA Seasonal Patrol · Cold Water

Current Danger Level

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Buoy Reading — View Buoy ↗

⚠ Data may be stale — showing last known reading. Conditions may have changed.

Swell Height*

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feet

Swell Period

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seconds

Direction

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swell from

Water Temp

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°F

NOAA Buoy 46026 — San Francisco Bar

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Long-Period Swell & Set Waves
Read the table above. Any swell period above 15 seconds means danger. Waves travel in sets separated by long, quiet intervals — sometimes as long as 20 minutes of calm. On long period days, stay aware! Do not approach the water's edge during a quiet stretch — that calm is when energy is building offshore.

Known Hazards at China Beach

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Deceptive Shelter

China Beach feels protected compared to Ocean Beach. On long-period swell days, this false sense of security is dangerous. The cove can focus and amplify incoming energy from certain swell directions.

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Rocky Boundaries

The cove is bounded by rocks on both sides. Wave surge on the rocks is hazardous, especially on larger swell days. Stay on the sand.

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Cold Water — Year Round

San Francisco Bay and ocean water is cold year round. Hypothermia can set in quickly. Always swim with a buddy and stay close to shore.

Before You Go Near the Water

Read the swell period before you approach the water. The number in the chart above is your warning. A period of 15+ seconds means sets are arriving with long, quiet intervals between them — sometimes up to 20 minutes of calm. Do not approach the water's edge during a quiet stretch — that calm is when energy is building offshore.

Watch the ocean. Stay on dry sand. Do not approach wet sand or the water's edge until you have watched the ocean and learned the rhythm of the sets.

Wet rocks or sand mark where the ocean has already been. If the rocks or sand are wet, a wave reached them recently. Stay above the wet line — always.

A long wait between waves is a warning. During long period swells, stay vigilant. The ocean may appear completely calm between sets. Do not be fooled. If it has been calm for several minutes, stay back. Do not walk toward the water.

Keep dogs on leash. Keep dogs on leash and away from the water's edge.

Tell someone your plans. Leave your destination and expected return time with someone before you go.

How to Read Sets

Long-period swell doesn't produce a steady stream of waves. It travels in sets — groups of larger waves separated by long, quiet intervals. At 15+ seconds, those intervals can stretch to 20 minutes of calm. Do not approach the water's edge during a quiet stretch — that calm is when energy is building offshore.

Find a high vantage point above the water line. Do not approach the shore first. Watch from above.

Time the quiet intervals. Count the seconds — or minutes — between large waves. This is your set interval.

Watch for at least 15 minutes. You need to see multiple sets before you understand the rhythm. One quiet stretch means nothing.

The largest wave in a set is not always the first. Sets build in size. The final wave is frequently the biggest.

When in doubt, stay back. At 15+ seconds period, stay completely clear of the shore and any rocks.

Ocean Emergency

911

GGNRA Dispatch · (415) 561-5505

USCG San Francisco · (415) 399-3547