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Ocean

Reading the swell

What the numbers on a buoy line mean, and why the Carmel side of the peninsula is not the same ocean as Monterey Bay. Live readings first, then the model forecast, every number linked to where it came from.

Buoys right now
Forecast for the next 90 hours

The swell, in words: loading the buoys. Buoy height is the average of the biggest third of the waves; period is the seconds between crests; direction is where the swell comes from.

The three numbers

Height

Bay (46236): — ft
Open coast: — ft

height

Significant wave height is the average of the biggest third of the waves. A diver feels it as surge: the push and pull at the entry and on the bottom grows with it.

Period

Bay (46236): — s
Open coast: — s

seconds

The seconds between crests. Short, under about 9 s, is local wind chop: choppy on top, with little effect below about 30 ft. Long, 14 s and up, is groundswell from a distant storm: it moves water on the bottom at 60 ft and surges in coves. A longer period also means the swell has travelled far, so the forecast for it is usually more reliable than the forecast for wind chop.

Direction

Bay (46236): —
Open coast: —

N NW

Where the swell comes from. Northwest is the usual winter swell. The bay's east beaches (San Carlos, State Beach, McAbee) are protected from northwest swell; the north beaches (Lovers Point, Coral Street) are a step harder in northwest swell; the Carmel sites face it. Exposure changes with direction.

Exposure notes come from a local instructor's public site and from our own scored record.

Why Carmel is different

  • Monterey Bay opens to the west, and the Monterey Peninsula sticks out on its south side. Northwest swell has to bend around Point Pinos to reach Monterey's beaches, and loses most of its energy doing it. That is why the mid-bay buoy reads lower than the open coast on northwest days.
  • Carmel Bay, Point Lobos and Monastery face the open ocean directly. What buoy 46239 off Point Sur measures is close to what those sites get.
  • Monastery is its own case: a steep beach with deep water close to shore, so waves do not lose energy before they break. A local instructor's public site gives a rule for Point Lobos by the reading at 46239: over 7 ft is "a bit surgy but still fine", over 9 ft is "a lot surgy", and over 11 ft is not worth going. Monastery is called off much earlier: in our scored record it is called off from about 6 ft at 46239.
  • Timing: a Carmel forecast needs the swell 6 to 12 hours past dive time, because the exit can be worse than the entry.
Point Lobos, by the reading at 46239
Over 7 fta bit surgy but still fine
Over 9 fta lot surgy
Over 11 ftnot worth going
Monterey Bay, the Monterey Peninsula and the coast south to Point Sur A simplified coastline from Santa Cruz south to Point Sur, with the mid-bay buoy 46236, the far offshore buoy 46042 and the Point Sur buoy 46239. 46236 46042 46239 Carmel BayPoint PinosMonasteryPoint LobosPoint Sur

Simplified drawing, not for navigation.

Northwest swell reaching the coast The same coastline with three arrows from the northwest showing swell heading toward Point Pinos and the open coast. The peninsula sits between the swell and the bay. NW swell 46236 46042 46239 Point PinosMonasteryPoint LobosPoint Sur

Northwest swell meets Point Pinos and the open coast first; the bay sits behind the peninsula.

What's in the water

Loading the buoy cards. If this stays empty, the buoy feed is down; the sources below still work.

See also an independent view of buoy 46236, a link only.

Your ocean board: arrange the data your way and test your own calls

Sources

Fetched —. Buoy data are NOAA National Data Buoy Center observations; the forecast is the CDIP MOP model grid.

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