El Niño is here and could be one of the largest on record, and California could be in for a rough ride.
While the weather pattern is often linked to a higher chance of more rain in Southern California, it can affect the state — and its famous coastline — in a number of ways. That is especially likely during a strong El Niño event, as this coalition has been.
In fact, there is a 63% chance that El Niño will be “very strong” later this year, according to the National Oceanic and Atmospheric Administration’s Climate Prediction Center. And there is an 88% chance that El Niño will be “very strong” or “strong.”
“The recently observed and continued increase in conditions in the tropical Pacific, along with the continued and increasingly extreme forward projections, suggest the possibility of something unusual,” wrote Daniel Swain, a UC climate scientist, in a blog post.
“The coming El Niño event – which is very likely to be very strong or historic in magnitude – will likely lead to widespread and significant effects around the world,” he added. “It is possible, or even likely, that at least some of these effects will be unprecedented in the modern era, given the combined effects of a high-profile El Niño event and more than a century of global warming.”
The effects of El Niño are usually felt most strongly in winter. Here are five major ways California could be affected.
1. Wet and wild winter
Although not a given, El Niño could open the atmospheric floodgates in Southern California.
Of the last four “strongest” El Niños on record, two — 1982-83 and 1997-98 — brought the Southern California coast more than double its normal annual rainfall. Another, in 1991-92, brought 133% of the average, according to data provided by Jan Null, an adjunct professor at San José State University. But the last one – in 2015-16 – did not meet expectations, with only 77% of the annual rainfall in the Southland.
According to NOAA, stormy weather is more common in the southern United States during El Niño. The Pacific Northwest, on the other hand, often experiences cold winters.
“A very strong El Niño event may be the single most important predictor of an increase in abnormally wet conditions, and an increased likelihood of heavy rain events, in any given winter in California — and perhaps also an early warning of an increased risk of major flooding events,” Swain wrote.
Despite the threat of flooding, a wet winter could bring relief to the Colorado River basin, which is “in the worst drought in years,” Swain wrote.
2. Heavy floods
More high tide flooding is possible in El Niño.
“A rise in sea levels along the US West Coast is likely, causing high tides and strong currents to ride higher and move further inland than usual,” NOAA said in a statement.
The agency’s experts noted that the El Niños of 2015-16 and 2023-24 brought more frequent, deep and widespread floods, a risk worsened after decades of sea level rise.
A man on a bicycle with his dog wades through flooded Greenock Lane after the area was hit by water during the high tide on Dec. 28, 2023 in Ventura.
(Brian van der Brug/Los Angeles Times)
The 2015-16 El Niño brought “record coastal erosion to many California beaches,” according to the California Coastal Commission.
“Large El Niño events can raise local sea levels by six to 10 inches in California during the winter monsoon and storm season through a combination of northward-propagating Kelvin waves along the coast and increased warming of ocean water,” Swain wrote. “Major coastal flooding is likely later this year.”
3. Warm water and temperatures
One of the components of El Niño is triggered when the trade winds in the Pacific Ocean – winds that blow reliably from east to west – weaken. That allows sea level to rise slightly, “and creates what we call a Kelvin wave downwelling,” said Jon Gottschalck, chief of the Climate Prediction Center’s forecasting operations branch.
That is not an ocean wave at the surface but one that moves warm water from the surface to the bottom. And the wave will “bring warm water from the western Pacific to the central and eastern Pacific,” Gottschalck said.
The next ingredient to El Niño is seeing how the eastward movement of warm water changes wind patterns.
The warm water moving from the west to the east also reduces the winds from the west to the east, allowing even more warm westerly water to move into the eastern Pacific. “It’s kind of a positive feedback. And once that happens, the El Niño event will develop and intensify,” Gottschalck said.
El Niño-induced warming of waters off the coast of Mexico, Central America and northern South America tends to move the atmosphere southward in the southern United States, “which can bring wetter than normal conditions to our region” during the winter, said Ariel Cohen, a meteorologist at the National Weather Service’s office in Oxnard.
El Niño will likely contribute to record-breaking temperatures around the world, Swain wrote.
(Paul Duginski/Los Angeles Times)
4. Sharks and other marine animals
Warmer waters could attract more beach visitors to the California coast.
“In the near future, we may expect to see an increase in tropical or subtropical species, which may include increased shark sightings off the coast of southern California,” said Nate Jaros, Aquarium of the Pacific’s vice president of fish and invertebrate conservation. “In very rare cases, even whale sharks have visited Catalina, including the 2015-2016 El Niño events.”
Marine mammals and other migratory species may also move closer to shore, “because they go where their food is,” said Andrew Leising, an oceanographer at the National Oceanic and Atmospheric Administration’s Southwest Fisheries Science Center.
El Niño in the past has been associated with large sablefish found near shore, and abundant rockfish larvae.
Warmer ocean temperatures could increase the presence of sea jellies and other gelatinous organisms, Jaros said.
A jellyfish-like creature called Watch it watch italso known as wind sailors, they can wash up on the West Coast and are generally harmless to humans. However, “in past El Niño events, we have seen a similar-looking Portuguese man-of-war, a very rare visitor to our waters, washing up on our beaches.” These animals can have a very painful sting,” said Jaros.
In the past ocean warming period called “The Blob,” which was followed by a very strong El Niño, scientists saw more tuna coming closer to the coast, going north, “and arriving earlier than in other years, and that actually leads to increased fishing opportunities for those migratory and large fish species,” Leising said.
5. But some marine life can struggle
Although not the sole function of El Niño, warmer ocean waters can wreak havoc on marine life.
There are currently two non-El Niño-related ocean heat waves near California — one off the southern coast of the state that began in December, and one farther west along the coast of Northern California and Oregon that began in May, according to data shared by Leising.
There are two oceanic heat waves off the West Coast right now, neither of which are influenced by El Niño at this time. One is off the coast of Southern California and the other is further offshore and west of Northern California and Oregon.
El Niño tends to create ocean heat waves, Leising said.
“One of the most important things, however, for animals in the environment is not how hot it is – which is important in some cases – but how long they are closed from the heat,” said Leising. “We have a situation, especially in Southern California, where we already have this heat wave in the ocean, and we’re just going to go further into the heat brought by El Niño.”
Past ocean heat waves have decimated California’s kelp, “with bull kelp habitats down 90% in Northern California since 2014,” Jaros said.
“The effects of this decline are spilling over to other species, including the endangered white abalone.
In past strong El Niños, scientists have seen a decline in plankton – an important food source for marine life – and an increased likelihood of harmful algal blooms.
Past strong El Niños have also brought low abundance, and a northward shift, of squid to the market, Leising said.
“We often see in the past when El Niños reduce the productivity of California sea lions, and the pups tend to be smaller,” Leising said.
The previous combination of “The Blob” – which hit the West Coast more than a decade ago – followed by a very strong El Niño led to “several closures of crab and shellfish fisheries due to harmful algal blooms,” according to Leising.
“We’ve increased whaling because the whales, again, are closer to shore, encountering more ships and other fishing gear,” Leising said. “And we also lost habitat for ground-dwelling fish because the oxygen level, where they live, was low.”
There have also been die-offs of seals, sea lions and seabirds, Leising said, probably due to a combination of food shortages and harmful algal blooms, as well as less food for baleen whales.
