CALIFORNIA — Climate scientists predict the current El Niño will be the strongest of the century, with models indicating a high probability of severe coastal impacts across California. The US National Oceanic and Atmospheric Administration expects the weather system to intensify in the fall and winter and persist until early spring 2027.

Daniel Swain, a climate scientist, described the developing pattern as strengthening ultimately to a very strong or so-called Super El Niño. "That's what that term means, it's a tier higher than strong, it's very strong, and could even become potentially the strongest on record," he said. A super El Niño is defined as an event where sea surface temperatures climb by at least 2C, and as of early 2026 there have been five super El Niño events in recorded history.

Swain stated that warming in the tropical eastern Pacific Ocean is already underway and evolving rapidly. "Just looking at the maps, even this week, things are changing very quickly now in recent days," he said. According to KQED, he stated there is a 90% confidence level that a record-breaking El Niño event will occur, which could intensify storms, heat up ocean water off the California coast, and temporarily raise sea levels.

However, he cautioned that the timing of these effects remains uncertain. "But the big impacts will probably not arrive for a couple of months, later in the fall into winter," he said.

Experts said the most significant impacts could occur around late December, January, February or March. A model from the European center for Medium-Range Forecasts indicates California has a 70%-100% chance of experiencing above-average rainfall along its coast. "El Niño is never going to guarantee any particular outcome in any California winter," he said.

Despite this uncertainty, the potential for extreme weather remains high. "That will likely affect and increase the likelihood of coastal flooding, particularly during strong storm events or during king tide events," he said.

Mark Merrifield, a Scripps Institution of Oceanography scientist, warned of historic water levels. "Likely the highest sea levels ever recorded on the California coast associated with this event," Merrifield said. He explained that those conditions are going to cause the beaches of California to erode and narrow, noting it is well documented that during El Niño events beaches across the entire state tend to move landward by about 30 meters or so. "With less beach in front of the coastline, the waves will have even greater impact on the shoreline with more likelihood of flooding and undercutting of cliffs," Merrifield said.

The physical transformation of the coastline poses direct risks to residential areas. Joel Lisonbee, a senior associate scientist at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder, emphasized the severity of such wet conditions. "It would have to be exceptionally wet," Lisonbee said. "That would also mean flooding, and the destruction and potential loss of life that comes along with that." He noted that many California homeowners do not carry flood insurance, leaving them financially exposed to these potential damages.

Historical data provides a baseline for the potential scale of destruction. The California Coastal Commission reported that a 1982-83 El Niño weather system destroyed 33 oceanfront homes and damaged 3,000 other residences. During the 1997-98 El Niño, California experienced massive flooding and 17 storm-related deaths.

State officials reported record coastal erosion on California beaches during the 2015-16 El Niño winter. These past events illustrate the recurring nature of the threat, although El Niño is not expected to completely erase drought in the US south-west.

The impacts of El Niño extend beyond the West Coast. Areas of the US Gulf coast and east coast, from Florida to the mid-Atlantic region, face high odds of increased precipitation. The US National Oceanic and Atmospheric Administration states that central and south Florida have historically experienced more severe weather, including more tornadoes and flood events, during El Niño years.

An outbreak of strong tornadoes in central and south Florida during the 1998 El Niño winter led to 42 deaths and more than $100m in damage. FEMA has issued 74 federal disaster declarations for flood incidents in Florida since the programme began, with the most recent declared for an incident beginning 2023-04-12.

Merrifield framed the current situation as both a warning and a planning opportunity. "The El Niño, I think, is a good opportunity to sort of see where our vulnerabilities are throughout the state and what we can do to prepare," he said. "And it also is a sobering look at what we can expect with climate change." More than 5,700 people watched the virtual town hall led by State Sen. Mike McGuire where these risks were discussed. NOAA is tracking the ongoing 2023/2024 El Niño closely, having issued an El Niño Advisory in June 2023, and will continue to communicate the latest forecasting science and potential impacts of individual storm and wave events as the winter progresses.

Why It Matters

A potential 'Super El Niño' threatens historic sea levels and beach erosion that could undercut cliffs and flood residential areas without warning. Past events of this magnitude have destroyed thousands of homes and caused dozens of deaths, yet many homeowners remain financially exposed due to a lack of flood insurance. The anticipated severity extends beyond California, increasing the risk of tornadoes and flooding along the Gulf and East Coasts.