Guide

Small craft advisories and the marine zones

Checked September 24, 2026 against the National Weather Service.

The Marine tile repeats the National Weather Service’s forecast for the strip of water your town opens onto. This page explains which zone that is, what the advisories and warnings mean in numbers, and the one line in the forecast that is most often misread.

Five offices, and the lines between them

Five weather service offices forecast this state’s coastal waters, and this site reads all five. Most of it is Eureka. The water north of Point St. George, just above Crescent City, runs across the state line and is forecast from Medford — so Fort Dick and the Smith River read a different office’s forecast from Crescent City, a few miles away. Everything from Point Arena to Point Piedras Blancas is forecast from San Francisco: Point Arena and Gualala, the Sonoma and Marin coast, the city, San Mateo, Santa Cruz and Monterey down the Big Sur coast to the county line. South of Piedras Blancas the office is Los Angeles/Oxnard, from the San Luis Obispo board to the Orange board. And from San Mateo Point, just below San Clemente, to the Mexican border the water is San Diego’s.

The other lines that matter are headlands. Cape Mendocino divides Point St. George’s zone from the Lost Coast’s. Point Arena is where the office changes. Point Reyes divides the San Francisco office’s two zones — Bolinas, Stinson Beach and Muir Beach sit below it and read the southern one, and so does every town on the San Mateo board. Pigeon Point is where that southern zone ends and the Santa Cruz coast’s begins; Point Pinos is the Monterey board’s seam, and Point Piedras Blancas is where the San Francisco office hands over to Los Angeles/Oxnard, and San Mateo Point where Los Angeles/Oxnard hands over to San Diego.

The zones, and the ten-mile line

Each stretch is split in two: an inner zone out 10 nautical miles, and an outer zone from 10 to 60, between the same headlands. The inner zone is the one that matters for the surf, the bar and a small boat, and it is the one the board shows.

The outer zones are PZZ470 off Point St. George to Cape Mendocino and PZZ475 south of the cape; off the San Francisco office’s coast they are PZZ570, PZZ571 and PZZ575, ten to sixty miles out between the same headlands. Monterey Bay has no outer zone. PZZ535 is the bay itself, from Point Santa Cruz round to Point Pinos, and the open water outside it is PZZ560 and PZZ575. Davenport, above Point Santa Cruz, is on the open coast and reads PZZ560; every town from the Santa Cruz wharf round to the Pajaro River reads the bay, and so does the south shore from Moss Landing round to Pacific Grove. The forecast usually says the bay’s sheltered corners run lighter than its own numbers, and it says so in those words. The seam on the Monterey board is Point Pinos. Pacific Grove sits on it: Lovers Point and its harbour side are in the bay, Asilomar a mile round the corner is in PZZ565, and the board lists the town under the bay and shows both zones. From Pebble Beach south — Carmel, the Highlands and the whole Big Sur coast to the county line — the water is PZZ565, Point Pinos to Point Piedras Blancas, with PZZ576 its ten-to-sixty-mile half; the zone runs on into San Luis Obispo County past Ragged Point.

The Golden Gate is a seam too, and the bay has zones of its own. On the San Francisco board Ocean Beach and Fort Funston are on the open coast in PZZ545, the same water as Pacifica. Baker Beach faces the Gate, and from Sea Cliff round the Marina and the Wharf to Treasure Island the water is PZZ530, the weather service’s zone for the bay north of the Bay Bridge (its full name runs on through San Pablo Bay, Suisun Bay and the West Delta, which are the same forecast). South of the bridge — the Bayview and Candlestick — is PZZ531. The bay zones are inland water: they carry wind and a chop, not the ocean’s swell, and a small craft advisory on the bay is usually the afternoon westerly through the Gate. The same forecast product also carries a San Francisco Bar section — the deep-water channel, the swell across the bar and the maximum ebb — which is the only word on the Golden Gate bar. The marine tile on the San Francisco board carries it under the open-coast zone, in the weather service’s own lines: it is a forecast, not a Coast Guard observation, so it sits with the forecast and there is no bar tile.

Point Piedras Blancas is where the fourth office begins. South of it the coast is forecast from Los Angeles/Oxnard, and the whole San Luis Obispo board — San Simeon to Oceano — is one zone, PZZ645, Point Piedras Blancas to Point Sal, with PZZ670 its ten-to-sixty-mile half. There is no seam on that board: every town reads the same forecast, and the Morro Bay bar report on the Bar conditions tile is the Coast Guard’s observation, not part of this product. That office writes its periods with a Wave Detail line — each swell train by direction, height and period — after the seas; the tile prints the seas and the detail stays in the period’s own text.

Point Conception turns the coast, and the channel is one zone. East of the point the shore faces south and the Channel Islands stand across the water; the whole Santa Barbara board, Gaviota to Carpinteria, and the whole Ventura board, the Rincon coast to Port Hueneme, are PZZ650, the east Santa Barbara Channel from Point Conception to Point Mugu, with PZZ673 its outer half out past the islands. The forecast splits the channel into a western and an eastern portion inside a period when the two differ, and the tile prints the period as written. The county’s west coast, Point Sal down to Point Conception, has no inner zone at all — PZZ673 runs from the beach to sixty miles — which is one of the reasons no town north of the point is on that board.

Point Mugu to San Mateo Point is one zone, and Catalina is inside it. The whole Los Angeles board, Zuma to Long Beach, is PZZ655, the inner waters of the bight from Point Mugu to San Mateo Point, with PZZ676 its outer half beyond the islands. The zone takes in Santa Catalina and Anacapa Islands by name, so Avalon reads the same forecast as San Pedro, twenty-seven miles across the channel. Long Beach’s own harbour lies behind the federal breakwater, outside the zone; the forecast is for the water beyond it. The whole Orange board, Seal Beach to San Clemente, is the same zone, and it is where the zone ends: at San Mateo Point, just south of San Clemente, NWS San Diego’s own waters begin. So on that board the marine tile is Los Angeles/Oxnard’s forecast while the weather tile is San Diego’s.

The East Bay reads the bay’s own two zones from the other shore. Richmond, Berkeley and Emeryville, and the whole of the Carquinez Strait from Rodeo to Antioch, are PZZ530, whose full name takes in San Pablo Bay, Suisun Bay and the west Delta; Oakland, Alameda and San Leandro are PZZ531, the bay south of the Bay Bridge. These are the forecasts for small boats, sailboards and ferries inside the Gate, and the afternoon westerly through the Gate is usually their headline.

The North Bay reads PZZ530 too, from the far shore. Benicia, Suisun Bay and the Sacramento River at Rio Vista are inside it; Vallejo’s Mare Island Strait, Suisun City’s slough and the Napa River open onto it, so all five rows read the same zone. Up the strait and into the Delta the afternoon westerly is funnelled and often stronger than on the open bay. The land forecast for Vallejo, Benicia, Suisun City and Rio Vista is written by the weather service’s Sacramento office; the water is still San Francisco’s.

Marin’s bay side is on the Sonoma-Marin board, and reads the bay. San Rafael, Larkspur, Tiburon and Sausalito face Richardson Bay and San Rafael Bay, which are PZZ530 too, while the board’s ocean towns read PZZ540 and PZZ545 over the hill. The zone card each row shows is its own water.

So is San Mateo’s bay side, on the San Mateo board. South San Francisco, San Mateo, Foster City and Redwood City face the bay south of the Bay Bridge, PZZ531, while Pacifica to Pescadero read PZZ545 on the other side of the ridge. The bay’s afternoon westerly pours through the gap at San Bruno and is usually what a small craft advisory on PZZ531 is about.

San Mateo Point to the border is one zone, and it is San Diego’s. The whole San Diego board, Oceanside to Imperial Beach, is PZZ740, the coastal waters out to ten nautical miles, with PZZ745 its outer half out to sixty and San Clemente Island. NWS San Diego issues this forecast twice a day, where the offices to the north issue four, so the tile expects a new one about every twelve hours.

On the north coast, Humboldt Bay has zones of its own

Since April 2, 2019 the weather service has split Humboldt Bay into two zones: PZZ410, the Humboldt Bay Bar, cut down to “only the immediate harbor entrance (bar channel)”, and PZZ415, Humboldt Bay, the bay inside it. The bar gets its own zone because a bar behaves like nothing else nearby.

Those two zones are where an advisory or warning for the bay itself is posted, but the regular coastal waters forecast has no written section for either of them. For the entrance the Eureka office publishes a separate Humboldt Bay Entrance Channel Forecast, and cautions that “ongoing shoaling of the entrance to Humboldt Bay can impact the accuracy” of it. The Bar conditions tile is the Coast Guard’s report of what the entrance is doing now; the forecast is what it is expected to do.

What the words mean, in knots

These are thresholds, not moods. The National Weather Service publishes them:

• Small Craft Advisory. For the western coast, which covers this one: “sustained winds of 21 to 33 knots, and/or wave heights exceeding 10 feet (or wave steepness values exceeding local thresholds).” The service notes the thresholds are specific to geographic areas, and “small craft” is left undefined: it is up to you whether your boat and your experience are up to those conditions.
• Gale Warning. Sustained winds or frequent gusts “in the range of 34 knots (39 mph) to 47 knots (54 mph) inclusive.”
• Storm Warning. “48 knots (55 mph) to 63 knots (73 mph) inclusive.”
• Hazardous Seas Warning. “Wave heights and/or wave steepness values meeting or exceeding locally defined warning criteria.” A steep, short-period sea can be dangerous to a small boat at heights that would be fine in a long swell.

The line most often misread

A forecast of “seas 10 feet” does not mean the waves are ten feet. Seas means significant wave height: “the mean or average height of the highest one third of all waves.” Two thirds of the waves are smaller than the number. Some are very much larger.

So a ten-foot forecast is a forecast that includes twenty-foot waves. Read the number that way every time.

On the beach, not just on the water

The same swell makes the hazard people on the north coast are most often caught by, and it is not only theirs. The Eureka office’s beach safety brochure: “Sneaker waves can strike without warning. Sneaker waves surge high up on the sand with enough force to knock you down and drag you into the ocean.” Nationally, the service says they can run up the beach by at least 150 feet.

The same brochure says three to five people drown on the north coast each year to sneaker waves, cold water, or going into the ocean after a dog. Stay farther back than feels necessary, stay off logs at the water’s edge, and “never turn your back on the ocean.”

Sources

• National Weather Service Eureka, marine zones — the zone numbers and names
• National Weather Service Eureka, coastal waters forecast and those of Medford, San Francisco, Los Angeles/Oxnard and San Diego — the forecasts the tile reads
• National Weather Service, marine zone change notice, effective April 2, 2019 — the Humboldt Bay Bar and Humboldt Bay zones
• National Weather Service, marine warning and advisory definitions and marine forecast FAQ — the thresholds, and the caution about individual wave heights
• National Weather Service Eureka, beach safety brochure and sneaker waves