Cowell Ranch
State Beach

Faces W · Remote · Rocky Shore · No Lifeguard · No Cell Service

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

*Many conditions factor into the size of breaking waves. This buoy information is taken in the open ocean and does not reflect shoreline conditions.

NOAA Buoy 46012 — Half Moon Bay

Known Hazards — Cowell Ranch

🪨

Powerful Shore Break

Waves break powerfully onto the beach. The force is sufficient to cause injury and immediately pull people into the water.

📵

No Cell Service

Cell service is limited or unavailable at this beach. Do not rely on your phone to call for help. The trail in is over a mile — tell someone your plans before you leave the trailhead.

🌡️

Cold Water — Year Round

Pacific water here is cold year round. Hypothermia can set in quickly.

Before You Go Near the Water

Read the swell period before you approach the water. The number above is your warning. A period of 15+ seconds means sets are arriving with long quiet intervals between them — sometimes 5 to 10 minutes of calm.

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 mark where the ocean has already been. If the rocks are wet, a wave reached them recently. The next set is coming to the same place. 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 before you hike in. Cell service is limited or unavailable at this beach. Do not rely on your phone to call for help. Leave your destination and expected return time with someone before you leave the trailhead.

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 reaching the shore. 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 each set is not the last one. Sets often build in size. The final wave of a set is frequently the biggest.

When in doubt, stay back. If the swell period is above 12 seconds, assume the next set will reach further than the last. At 15+ seconds, stay completely clear of the shore.

Ocean Emergency

911

CA State Parks Emergency · (800) 952-5580

USCG San Francisco · (415) 399-3547