A Southern California winter at the beach can look nothing like the one before it, and El Niño is often the reason. Warmer water, bigger swell, narrower beaches and runoff after storms can all ride along with it. This El Niño Southern California guide explains what the pattern is, how it tends to change our ocean, what past events did to the coast, and how to stay safe in the water this season.
This season is not hypothetical. In its September 10, 2026 ENSO diagnostic discussion, NOAA's Climate Prediction Center (CPC) had an El Niño Advisory in effect and gave a greater than 90% chance of a very strong event through fall and winter 2026-27. The next update is scheduled for October 8, 2026.
Advisory
El Niño alert status, Sept. 10, 2026
NOAA CPC
+1.8°C
Niño-3.4 temperature anomaly, August 2026
NOAA CPC
90%+
chance of a very strong event, fall and winter 2026-27
NOAA CPC
75%
chance of a record-strength event, Oct. to Dec. 2026
NOAA CPC
What is El Niño?
El Niño is the warm phase of a Pacific climate cycle called the El Niño-Southern Oscillation, or ENSO. The cycle has three states: El Niño (warm), La Niña (cool) and neutral, when neither one is in control.
In a typical year, trade winds blow west along the equator and push warm surface water toward Asia. Cold, nutrient-rich water rises from the deep along South America to replace it. During El Niño, the trade winds weaken. Warm water drifts back east toward the Americas, and that upwelling weakens or stops.
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The name is centuries old. NOAA notes that South American fishermen noticed unusually warm water in the 1600s and called it El Niño de Navidad, because it tends to peak around December. Events come every two to seven years on average and usually last nine to 12 months, though some run longer.
How does NOAA declare an El Niño?
Since February 1, 2026, CPC has tracked ENSO with the Relative Oceanic Niño Index (RONI). It compares sea surface temperatures in the Niño 3.4 region of the central Pacific with the average across the global tropics. El Niño means that relative anomaly is +0.5°C or warmer, and La Niña means -0.5°C or cooler. In the historical record, an event counts when the threshold holds for at least five overlapping three-month seasons.
CPC also runs an ENSO Alert System. An El Niño Watch means conditions are favorable for El Niño within the next six months. An El Niño Advisory means El Niño conditions are observed and expected to continue.
El Niño vs La Niña: what's the difference?
| El Niño | La Niña | |
|---|---|---|
| Trade winds | Weaker than usual | Stronger than usual |
| Upwelling off the Americas | Weakens or stops | Increases |
| California coastal water | Tends warmer, fewer nutrients | Colder, more nutrients |
| Typical winter tilt, southern U.S. | Wetter | Drier |
| Marine life off California | Warm-water species move in | Cold-water species like squid and salmon |
Both patterns shift the odds rather than writing the forecast. A strong El Niño raises the chance of certain impacts, and CPC itself notes those impacts are more likely but not guaranteed.
How does El Niño affect Southern California?
El Niño ocean temperature: warmer water at the beach
Scripps Institution of Oceanography scientists describe two ways El Niño warms our coast. In fall and winter, shifting winds over the North Pacific push warmer offshore water toward the normally cool coastline. Meanwhile, slow ocean waves traveling along the coast below the surface press the warm layer deeper, which suppresses the cold upwelling that usually keeps Southern California water brisk.
This year the ocean got a head start. A marine heat wave developed off the West Coast before El Niño matured, and Scripps reported in August 2026 that its Scripps Pier station had already logged 42 days that year with record-high temperatures for the date. Record highs showed up at all ten of its Shore Stations sites along the California coast.
Warm water feels like a gift in November. The catch is that it can tempt more people into the ocean during the same months El Niño tends to deliver bigger surf.
Bigger winter surf and higher sea levels
El Niño reshuffles North Pacific storm tracks. Scripps says its wave buoys typically record high surf beginning in late autumn and early winter during El Niño, and that storms tend to arrive closer and from directions our offshore islands shelter less. Strong events can also raise sea level along the California coast by about 6 to 12 inches, because warmer water expands.
Stack that higher baseline with a high tide and a big swell, and flooding risk jumps. Scripps adds that back-to-back storms are especially damaging, since the first one strips the sand and the next one hits a beach with no buffer. This season's king tides land on December 23-25, right in El Niño's prime window. Our guide to the types of tides covers why those dates matter.
Beach erosion
After the 2015-16 El Niño, USGS-led researchers surveyed 29 beaches from Washington to Southern California. Winter erosion ran 76% above normal, by far the highest ever recorded, and most California beaches eroded beyond historical extremes. Wave energy that winter equaled or exceeded measured historical maximums along the West Coast. Recovery can be slow: after 1997-98, some beaches took a decade to come back.
Rain, runoff and water quality
A study of California records from 1901 to 2010 by Columbia University researchers found El Niño's influence on rainfall is stronger in the south than the north, and stronger in late winter. In eight of ten moderate-to-strong El Niños, Southern California's late-winter rainfall landed in the wettest third of years.
It is still not a sure thing. The 2015-16 event was one of the three strongest on record, yet USGS reports Southern California received 70% less rainfall than during the two previous big El Niños. A NOAA research team later documented that winter's dryness, the opposite of what seasonal forecasts had suggested.
When heavy rain does come, runoff matters for swimmers. LA County Public Health warns that bacteria levels can stay elevated for up to three days after significant rain, especially near flowing storm drains, creeks and rivers.
What does El Niño mean for beach safety?
Most El Niño hazards are familiar ones turned up a notch. Here is what we watch for:
- Bigger, more frequent swell. More wave energy means stronger rip currents and heavier shorebreak. Review how to spot a rip current and check the surf forecast before every visit.
- Higher water. Raised sea levels plus king tides leave less beach, flood access points and push waves up to bluffs and seawalls. Stay off jetties and wave-washed rocks.
- Warm water that feels safe. Comfortable temperatures don't make winter surf any gentler.
- Runoff. Respect rain advisories and stay away from storm drain outflows.
- Shifting sandbars and narrower beaches. Conditions can change storm to storm, so don't assume a beach is the same as last month. Our guide to reading ocean conditions shows what to look for.
El Niño Southern California history: past strong events
2.4°C
peak RONI in 1982-83, highest since 1950
NOAA CPC
2.3°C
peak RONI in both 1997-98 and 2015-16
NOAA CPC
76%
above-normal winter beach erosion, 2015-16
USGS
6-12 in
sea level boost on the California coast in strong events
Scripps
1982-83
CPC's relative index peaked at 2.4°C across late 1982 and early 1983, the highest value in a record that begins in 1950. A 1984 National Research Council report estimated that winter's California coastal erosion and storm damage at several hundred million dollars and listed about $8 million in damage to the Santa Monica Pier and nearby recreational facilities. The report noted that big waves arrived at the same time as large tidal ranges. NOAA's Santa Monica tide gauge still lists its highest observed water level on November 30, 1982.
1997-98
The relative index peaked at 2.3°C. Scripps counts 1997-98 among the strongest El Niños ever recorded, and USGS notes some West Coast beaches needed about a decade to recover from it.
2015-16
Another 2.3°C peak, paired with record erosion and record-level wave energy but surprisingly little Southern California rain. Marine life shifted too. Scripps documented pelagic red crabs, which normally breed off Baja, washing up in San Diego in June 2015. During the warm years of 2014 to 2018, which combined a marine heat wave with El Niño, its Marine Vertebrate Collection recorded 36 new and rarely seen species in California waters.
Marine life shifts you might notice
With weaker upwelling and fewer nutrients, El Niño reshapes the food web. NOAA says warmer water can bring tropical species such as yellowtail and albacore into areas usually too cold for them. Scripps researchers add a few local patterns to watch:
- Kelp stress. Giant kelp needs cool, nutrient-rich water, and El Niño brings the opposite plus more damaging winter swell.
- Sharks. During the last strong El Niño, juvenile white sharks were seen at Southern California nursery sites in much higher numbers than normal, and Scripps researchers expect a similar pattern this year. Follow posted advisories and lifeguard instructions.
- Sea lions. In past warm events, mothers traveled farther for food and many pups became undernourished or stranded. If you find one on the beach, keep your distance and tell a lifeguard.
Planning a beach or pool event during El Niño
Beach events. Build in a rain date, and plan around both the tide chart and the surf forecast. Avoid scheduling water activities on king tide days or within three days of heavy rain. If guests will be in the water, a private lifeguard gives you a trained set of eyes on changing conditions. See our service areas for coverage from Ventura County to Orange County.
Pool events. Scripps notes that an El Niño-boosted marine heat wave can make coastal air slightly warmer and more humid in summer and fall. Warm fall days are pool days, so keep your supervision plan in place after summer ends. Our pool party safety checklist and guide to how many lifeguards you need can help, and you can review pricing anytime.
How to check the current El Niño status
CPC's ENSO diagnostic discussion is the official source. It comes out monthly and lists the alert status, a one-line synopsis and the odds for the coming seasons. For local effects, pair it with your National Weather Service office's surf and beach forecasts, NOAA tide predictions and LA County Public Health's beach water quality page.
El Niño won't decide every storm this winter, but it loads the dice toward warmer water, bigger surf and higher water levels. Plan with that in mind, and keep a lifeguard between your guests and the ocean.