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37 Feet and Holding: San Diego Is Having Its Clearest, Warmest Stretch of the Year

The Scripps pier cam has graded 28 feet or better every day since July 30, the water has been running near the warmest ever recorded at the pier, and NOAA expects El Nino to strengthen through the fall.

Nick Meyers, Nautical Nick16 min read

The view from the Scripps Pier underwater camera at 9:00 AM on July 30, the first 37-foot reading of the run, with fish sprinkled through the frame and the rippled seafloor in plain view. Every underwater image in this story comes from that camera, operated by UC San Diego's Coastal Ocean Observing Lab.

37 Feet and Holding: San Diego Is Having Its Clearest, Warmest Stretch of the Year

At 3:17 in the afternoon on August 5, the camera under Scripps Pier looked down a line of pilings that simply kept going. Baitfish drifted through the whole frame, a few larger green-backed fish held mid-water, and the sightline ran out to 37 feet, tying the clearest reading the camera has ever produced. Earlier that same morning a spiny lobster had parked itself directly on the dome, antennae across the lens, while the water behind it stayed at 35 feet.

Baitfish scattered through clear blue water along the Scripps Pier pilings, which fade into the distance.

The 37-foot reading at 3:17 PM on August 5, matching the July 30 mark for the clearest frame in the archive. Scripps Pier underwater camera.

La Jolla is in the middle of the best sustained clear-water run since the pier-cam program began in mid-July. Every daily median since July 30 has graded 28 feet or better, an 8-day streak, and most daytime captures since August 1 have landed between 28 and 37 feet. The water is also unusually warm. NOAA's station on the pier logged daily highs of 76 to 77 degrees Fahrenheit all week, within about 2 degrees of the warmest reading ever taken there. Divers who have been waiting all summer for a window are in it right now, and the reasons it opened are worth understanding, because they also say something about how long it might hold.

What the Camera Has Been Seeing

The run started with a familiar frustration. On August 1 the cam read 33 feet at dawn, held in the low 30s through midday, then collapsed to 6 feet by 3 PM. August 2 did the same thing, excellent through the morning and green by mid-afternoon. That daily crash is the normal summer pattern in La Jolla, where afternoon wind and swell stir the shallows.

A calico bass swims close to the underwater camera in blue water beneath Scripps Pier.

A calico bass noses in for a close look at the camera at 10:11 AM on August 2, graded 28 feet. Scripps Pier underwater camera.

Then it stopped crashing. On August 3 the clear water held all the way through the evening captures, still at 32 feet at 5:15 PM. August 4 stayed at or near 30 feet nearly all day. August 5 did something the archive had not recorded before: it got better as the day went on, climbing from 33 feet in the morning through a run of 35-foot readings to the 37-foot peak in mid-afternoon. On the morning of August 6 the camera was still reading 33 to 35 feet.

A calico bass hangs in open blue water near the Scripps Pier pilings, with a second fish near a piling behind it.

Open blue water at 5:15 PM on August 3, graded 32 feet, the first evening the clarity held. Scripps Pier underwater camera.

The pier sensors agree with the pictures. Chlorophyll, the pigment in the microscopic drifting plants that turn coastal water green, held between 0.44 and 0.49 micrograms per liter all week, which is blue-water territory for a Southern California beach in August. Turbidity, a measure of suspended particles in the water, fell from 0.35 to 0.17 NTU over the same stretch.

Two spiny lobsters meet face to face at the top of a Scripps Pier piling in clear blue water.

Two spiny lobsters kissing on the front right piling at 11:00 AM on August 3, graded 30 feet. Scripps Pier underwater camera.

What Is Causing It

Two things line up, and both matter.

The first is swell. The morning reading at La Jolla Shores faded from 3.2 feet at a 10-second period on August 1 to 1.6 feet at 12 seconds by August 6. A small, long-period south swell moves water without churning the bottom, so the sand stays down and the sightline stays open.

Sunbeams cut through clear, empty blue water under Scripps Pier at dawn.

Dawn light in glassy water at 6:48 AM on August 1, graded 33 feet. Scripps Pier underwater camera.

The second is what is missing from the water. Along the California coast, cold, nutrient-rich water normally wells up from below in a process called upwelling, which feeds blooms of plankton and turns the water green. Warm surface water suppresses that upwelling. Fewer nutrients reach the surface, less plankton grows, and the water turns warmer, bluer, and clearer. The chlorophyll numbers this week are the signature of a coast whose upwelling has been switched down, which is also why the water is so warm. The clarity and the heat are the same story told 2 ways.

The Water Is Close to Its All-Time High

Someone has measured the temperature of the water at the end of Scripps Pier nearly every day since 1916, which makes it one of the longest continuous coastal ocean records anywhere. The warmest reading in that entire record is 79.4 degrees Fahrenheit, set in August 2018. This week the NOAA station on the same pier peaked at 77.4 degrees on August 3, with daily highs of 76 to 77 through the week.

That is close to the top of a 110-year record, and it is well above the long-term average for early August, which the Scripps Shore Stations program plots against every daily reading. It is worth noting the record and this week's numbers come from 2 different instruments on the same pier, Scripps' own shore station program and NOAA station 9410230, so the comparison is close but not exact.

There is a wrinkle in the temperature data that matters more to divers than the headline number. The daily lows this week ran from 64.6 to 70.9 degrees, a swing of 10 degrees or more inside a single day. That is cold water pulsing up from the La Jolla submarine canyon, which sits just off the end of the pier. The surface is bathwater. What is underneath it is not.

The El Nino Question

NOAA has an El Nino Advisory in effect and its forecasters expect a strong event peaking between October and December. The phrase "super El Nino" is media shorthand rather than anything NOAA says, so it is worth treating the label loosely and the forecast seriously.

The important detail for anyone planning dives is the timing. El Nino has not caused this week's conditions. The warm water sitting off Southern California right now is a marine heatwave driven by weakened winds and suppressed upwelling, running on top of a steadily warming ocean. El Nino is the reinforcement arriving behind it, and it is forecast to keep the upwelling suppressed and the water warm through the winter rather than to let it relax.

The camera caught the argument swimming past. At 8:11 on the morning of August 2, a finescale triggerfish crossed the lens at Scripps Pier. It is a warm-water fish whose center of abundance runs from the tropics north to southern Baja California, and it was long considered rare above that line. It has turned up in Southern California more often in recent years, and marine surveys note that its numbers here have risen after previous El Nino events. A triggerfish at the end of a San Diego pier is not proof of anything on its own. It is the kind of visitor that shows up when the ocean is running warm, which is exactly what the temperature record says it has been doing.

A finescale triggerfish, pale and spotted with a dark-edged fin, glides past the underwater camera beneath Scripps Pier.

A finescale triggerfish passing the camera at 8:11 AM on August 2, graded 30 feet. Its home range centers far to the south, and it reaches San Diego mainly in warm-water years. Scripps Pier underwater camera.

For divers, a strong El Nino generally means more of what La Jolla has had this week: warmer water, less plankton, and better offshore visibility. It also means bigger winter storms, and storm runoff is the fastest way to turn clear water brown. The clean water and the dirty water are likely to arrive in the same season.

What It Means for Spearfishing

Wetsuit. At 76 degrees on the surface, plenty of divers are comfortable in a 3 millimeter suit, and some are getting away with less on short shallow dives. The daily lows tell the other half of the story. With water pulsing up from the canyon in the mid-60s, a spearo who drops down a wall or spends 2 hours in the water can end the session much colder than the surface reading suggests. Bringing more suit than the surface temperature calls for remains the safer call, especially near the canyon edge.

Fish. The cam has been full of life all week, with dense baitballs filling entire frames, bait streaming past both piling lines, and larger fish working the edges. Bait in the water is the honest indicator; the predators follow it. Calico bass have been in frame repeatedly, close enough to the lens to read the mottling on their flanks.

A massive school of baitfish fills the entire frame in clear blue water under Scripps Pier.

The baitball that swallowed the camera at 1:38 PM on August 5, with the water behind it graded 35 feet. Scripps Pier underwater camera.

Tropical visitors. Warm water pushes warm-water species north. In past strong El Nino and marine heatwave years off Southern California, that has meant yellowtail and dorado ranging farther up the coast, hammerhead sharks and bluefin tuna appearing well north of their usual range, and in some years swarms of pelagic red crabs washing onto beaches. Cold-water species move deeper or farther north in the same conditions. The catch changes at least as much as it improves. The triggerfish on the pier camera is the first of those changes to show up on this stretch of coast.

Legality, which matters more than usual here. The clearest water in San Diego sits inside a complex of marine protected areas. The Matlahuayl State Marine Reserve, covering the water around La Jolla Cove, is no-take, meaning nothing may be removed. The San Diego-Scripps Coastal State Marine Conservation Area in front of the pier is also tightly restricted, and South La Jolla holds another reserve and conservation area with their own rules. The boundaries are specific and the allowances differ from one area to the next, so anyone planning to spear should pull the current CDFW boundary maps and regulations before getting in the water rather than relying on a general description. The Point Loma kelp beds are the nearby alternative most San Diego spearos work.

One more note prompted by the camera: the lobsters showing up on the pilings and the lens are a good sign for the fall, but the recreational spiny lobster season is closed in August and opens later in the year. Check CDFW for this season's exact opening date before making plans around them.

Extreme close-up of a spiny lobster sitting directly on the underwater camera dome.

A California spiny lobster parked directly on the camera dome at 10:50 AM on August 5, while the water behind it graded 35 feet. Scripps Pier underwater camera.

Where to Dive It

The clear water has not been a La Jolla exclusive. It has been running up and down the coast. Lifeguards at Newport Beach called 15 feet on August 7 and again on August 8, and Laguna Main Beach called 15 to 18 feet across the same stretch. Divers reporting from Orange County have been finding the same thing.

Where this site published low numbers for spots outside San Diego, that was our forecast underperforming, not the ocean. The model leans hardest on San Diego, where the pier camera and the lifeguard stations give it something to check itself against, and it has been shakier north of there. On the morning of August 6 it called 9 feet at Laguna Main Beach while the lifeguards, who read the worst water on the beach, called 18. A forecast that lands below the surf-zone number is not describing the ocean, and that is the failure being worked on.

One real caveat survives, and it cuts the other way. Lifeguards read visibility at the surf break, and the break is always the worst water on the beach. Their morning calls at La Jolla Shores ran 20 feet while the camera along the pier read 30 or better. Both numbers are honest. The surf zone is stirred and the water past it is not, so the payoff belongs to divers who get outside the break, and the number to expect once the sand stops moving underfoot is the higher one.

A spiny lobster clings high on a Scripps Pier piling above a visible sandy bottom in clear blue water.

A spiny lobster out on a piling at 7:28 AM on August 5, graded 33 feet, with the bottom visible below. Scripps Pier underwater camera.

The best thing to do with water like this is not a dive at all. The swim from La Jolla Shores around to La Jolla Cove and back is the finest snorkel in Southern California, and a run of 30-foot visibility is the condition it was waiting for. The route crosses 4 habitats in a single outing: sea caves, kelp forest, rocky reef, and surfgrass beds. Leopard sharks gather off the Shores in the thousands from summer into fall, in water shallow enough to stand in. Soupfin sharks work the reserve kelp through the same months. Sea lions come out to meet swimmers near the Cove, green sea turtles turn up for the lucky, and the fish are simply everywhere. Bring a snorkel and nothing else, because the reserve is no-take.

For depth, the wall of the La Jolla submarine canyon runs off the Shores and is the reason the cold water pulses in. For spearfishing, work outside the protected areas, with the Point Loma kelp beds the standard choice. Boat divers with clear water to spend should consider the wrecks off Mission Beach, which reward exactly this kind of visibility.

How Long It Lasts

Nobody can forecast a specific sightline more than a few days out. What can be said is that the ingredients are still in place: swell is small and long-period, chlorophyll is pinned near the bottom of its range, and the camera was still reading 33 to 35 feet on the morning this report was filed. Nothing in that mix has turned yet.

The threats are the usual ones. A new south or west swell, a stretch of hard afternoon wind, or a warm-water bloom would all close the window quickly, and the first 2 days of this run showed how fast the afternoon can fall apart. Further out, the seasonal risk flips: if NOAA's forecast holds and El Nino strengthens into winter, the warm water and low plankton that opened this window are likely to persist, and the winter storms that come with a strong event are likely to slam it shut for days at a time.

Updated August 11

The run is still going, and it has come off its peak only slightly. The camera graded 33 feet at 6:50 on the morning of August 11 and 28 to 32 feet through the rest of that morning, against the 35 to 37 feet it was reading a week earlier. Every day the camera has captured since July 30 has held a median of 28 feet or better, a span that now covers 13 days.

The small dip has a visible cause. Chlorophyll climbed from 0.35 to 0.62 micrograms per liter between August 7 and August 10 and turbidity nearly doubled, which is a modest amount of plankton and sediment moving back into the water. Both eased again on August 11 and the camera ticked back up with them. Swell has crept from 1.6 feet to 2 feet and shortened to an 11-second period. The surface has come off the top as well, peaking at 73 degrees on August 11 against 77 a week earlier, though the daily lows still drop into the low 60s as the canyon pulses.

What that adds up to has stopped setting records and settled into something arguably more useful, which is consistency. Small surf, a long-period swell, wind of 2 to 4 knots most mornings, warm clear skies, and water in the low 70s holding 28 to 33 feet of visibility, every single day this week. That is about as good a run as this coast produces, and legendary is not too strong a word for it.

The camera at the end of the pier keeps looking down the same line of pilings, and it keeps seeing all the way to the end.

Rippled sand on the seafloor is visible beneath Scripps Pier in clear blue water, with small fish near a piling.

The rippled bottom still clearly visible on the morning of August 6, graded 35 feet. Scripps Pier underwater camera.

Correction

An earlier version of this report described the clear water as a La Jolla story rather than a Southern California one, and cited lifeguard surf-zone reports of 3 to 7 feet in Orange County and North County as evidence that the run stopped at the county line. That framing was wrong. The clear water has been regional, those figures describe the break rather than the water divers swim in, and the low numbers this site published for spots outside San Diego reflect a weakness in our own forecast model. The section above has been rewritten. A fish identified in the original as a possible shovelnose guitarfish has since been identified as a finescale triggerfish, and moved to the section on El Nino where it belongs.

Sources

37 Feet and Holding: San Diego Is Having Its Clearest, Warmest Stretch of the Year | Nautical Nick