2026 Super El Niño Forecast: What happens this winter could shock California, here's why

California could be heading toward an unusually dangerous winter as a rapidly strengthening El Niño threatens to push coastal sea levels to their highest levels ever recorded, increasing the risk of flooding, erosion and powerful waves along the state’s shoreline, according to The Los Angeles Times.

Scientists are watching the developing climate pattern closely as ocean temperatures across the tropical Pacific continue to climb. The World Meteorological Organization has forecast a rapid intensification into a strong El Niño during July-September 2026, with some models pointing to exceptionally warm conditions in the eastern and central Pacific.

The potential consequences for California extend well beyond rainfall. Higher-than-normal seas could combine with large waves, high tides and winter storms to put coastal communities under considerably greater pressure.

California sea levels could reach unprecedented heights

Mark Merrifield, director of the Center for Climate Change Impacts and Adaptation at UC San Diego’s Scripps Institution of Oceanography, warned that the developing El Niño could produce exceptionally high sea levels along the California coast.

According to the report, during a recent town hall, Merrifield pointed to satellite observations showing that sea levels in parts of the eastern Pacific were already elevated compared with the reference period. He expects the anomaly to become much more pronounced as the year progresses.

The timing could be particularly important. Sea levels associated with El Niño events typically reach their strongest levels toward the end of the year, meaning November and December could become critical months for California’s coastline.

Historical El Niño events have produced significant temporary increases in sea level along the West Coast. Merrifield said San Francisco has previously experienced anomalies ranging from roughly half a foot to a foot during major events.

That temporary rise may sound modest, but its impact can be substantial when combined with storm surge, high tides and large waves.

Why El Niño raises the water along the coast

El Niño begins thousands of miles from California, with unusually warm water developing across the central and eastern tropical Pacific.

That warmer water expands, contributing to higher sea-surface heights. Changes in atmospheric circulation and ocean currents can further redistribute water toward the eastern Pacific.

The developing 2026 event is already drawing attention because of how quickly ocean temperatures have risen. WMO forecasts indicate that the current El Niño is strengthening rapidly, with seasonal-average temperatures in key Pacific monitoring areas expected to exceed 2 degrees Celsius above normal.

NOAA researchers are also studying the consequences for the West Coast as conditions build toward what could become an extreme El Niño.

Beaches could lose a critical buffer

Higher sea levels are only one part of the concern.

El Niño can also generate stronger waves along California’s coastline. Repeated large waves can strip sand from beaches and push the shoreline farther inland.

Merrifield said California beaches have historically shifted landward by around 30 metres, or nearly 100 feet, during El Niño events.

That loss of beach width matters because sand acts as a natural buffer. Once that buffer is reduced, large waves can reach cliffs, seawalls, roads and other infrastructure with greater force.

The result could be a dangerous combination of elevated water, powerful surf and weakened beaches.

Southern California faces a bigger winter flood threat

Southern California could be particularly vulnerable if the strong El Niño develops as expected.

The climate pattern often alters the position of the Pacific jet stream and storm track, increasing the likelihood of wetter conditions across Southern California during the peak winter months.

However, The Los Angeles Times further reported that scientists stress that El Niño does not guarantee a wet winter. The powerful 2015-16 El Niño, for example, failed to produce above-average rainfall across Southern California.

This time, however, climate scientist Daniel Swain said the strength of the developing event could shift the odds substantially toward a wetter winter, particularly from late December through March.

That means California could face an unusual combination: higher seas arriving at the same time that powerful winter storms bring heavy rainfall.

When high tides, elevated sea levels, large waves and intense rainfall occur together, coastal flooding can become much more severe.

California has seen this before

The warning is not purely theoretical.

During the 2023-24 El Niño, significant flooding affected parts of Ventura, Los Angeles and San Diego counties. In Ventura, a powerful wave surged over a seawall and injured eight people.

Major El Niño events in 1982-83, 1997-98 and 2023-24 have also been associated with notable sea-level peaks around California.

The concern now is that another exceptionally strong event could arrive while long-term climate change has already raised the baseline sea level.

That means a temporary El Niño-driven increase is being added to a coastline that is already experiencing human-caused sea-level rise.

San Francisco Bay and Sacramento-San Joaquin Delta also at risk

The effects would not be restricted to Southern California.

Higher water levels could affect communities around San Francisco Bay and the Sacramento-San Joaquin Delta, areas already vulnerable to flooding and rising seas.

For San Francisco, historical strong El Niño events have produced substantial temporary increases in sea level. If a similar anomaly occurs this winter, high tides and storm activity could push water levels even higher.

The implications range from coastal flooding and erosion to saltwater moving farther into freshwater systems.

Warmer Pacific could trigger another marine heatwave

There is another concern beneath the surface.

The developing El Niño is expected to add more heat to an already unusually warm Pacific along parts of the West Coast. NOAA has warned that the existing marine heatwave and El Niño could combine to place additional pressure on marine ecosystems and fisheries.

Warmer water can weaken or suppress upwelling, the process that brings cold, nutrient-rich water from deeper parts of the ocean toward the surface.

That can affect the entire marine food chain, from microscopic organisms to commercially important fish and larger wildlife.

California’s kelp forests are also vulnerable. Previous marine heatwaves have contributed to severe declines in Northern California bull kelp, with consequences for species that depend on those habitats.

Domoic acid becomes another concern

Warmer ocean conditions could also increase the risk of harmful algal blooms involving Pseudo-nitzschia, an algae capable of producing the neurotoxin domoic acid.

The toxin can accumulate in shellfish and has been linked to illness in humans. At higher exposure levels, it can cause serious neurological symptoms.

Wildlife can be affected too, with marine mammals and seabirds among the animals that have suffered during previous toxic blooms.

California officials are therefore preparing to monitor domoic acid levels as the state approaches the Dungeness crab season.

The bigger warning behind the 2026 El Niño

The developing El Niño is not simply a story about hotter water in the Pacific.

It could influence California sea levels, winter storms, coastal flooding, beach erosion, marine heatwaves, fisheries and ocean ecosystems—sometimes simultaneously.

Scientists emphasize that forecasts still contain uncertainty, particularly over the exact peak strength and timing of the event. But international climate agencies agree that El Niño is strengthening rapidly. WMO says the pattern is increasing the likelihood of heatwaves, drought, heavy rainfall and other extreme weather in different parts of the world.

For California, the biggest concern may come later in the year, when high tides, storm-driven waves and elevated sea levels could converge, The Los Angeles Times reported.

If the developing El Niño follows the trajectory currently being forecast, the state could be heading into a winter when the ocean itself becomes a major part of the flood threat.