Full Breakdown
Kelvin Wave and El Niño Amplify California’s Coastal Flood and Erosion Risks Amid an Active Hurricane Season
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The Immediate Threat
An oceanic Kelvin wave generated by the 2026 El El Niño is moving along the West Coast, raising sea levels by several inches to a foot as it reaches California. The higher baseline water coincides with strong Pacific storms, including Hurricane Polo and Tropical Storm Odalys, generating 4-to-7-foot surf and high tides of about 7 feet. The “double whammy” prompted Governor Gavin Newsom to declare a statewide emergency and local jurisdictions—from Orange County to Long Beach—to issue coastal-flood advisories and evacuate vulnerable homes.
Background & Context
Kelvin waves are slow-moving subsurface disturbances that transport warm water eastward across the tropical Pacific. During a strong El Niño, repeated downwelling Kelvin waves deepen the thermocline, suppress cold-water upwelling, and push warm water toward the eastern Pacific, reinforcing the event’s intensity. Sea-level rise has already placed many California shorelines near historic high-water marks, so any additional elevation can markedly increase flooding and erosion potential.
Data & Statistics
- NOAA estimates a Kelvin-wave-induced sea-level rise of 6 to 12 inches.
- UC climate scientist Daniel Swain notes ocean levels off Southern California are already a foot higher than normal because of the El Niño.
- The National Weather Service (NWS) projects high tides of roughly 7 feet, nearly a foot above astronomical tides, for the Monday-Tuesday peak of the storm surge.
- Forecast surf heights for Los Angeles, Ventura and Santa Barbara counties range from 4 to 7 feet, with the Wedge in Newport Beach expecting the upper end.
- The NWS coastal-flood advisory, in effect as of September 28, 2026, covers Los Angeles, Ventura and Malibu beaches; a further advisory is scheduled for September 29, 2026.
Official Statements & Responses
- Governor Newsom’s emergency proclamation authorizes state resources for shoreline protection and evacuation support.
- NOAA oceanographer William Sweet described the situation as a “double whammy” of sea-level rise plus a strong El Niño-driven surge.
- The NWS issued a coastal-flood and high-surf advisory, urging residents to avoid low-lying walkways, parking lots and beach structures, and to prepare sandbags.
- Long Beach fire officials distributed about 4,000 sandbags and set up a mobile command post to coordinate shoreline defenses.
On-the-Ground Reports
- A sinkhole opened beneath a Malibu beachfront driveway owned by actor Nicolas Cage, disrupting a gas line and prompting evacuation of dozens of homes.
- Laguna Beach and Dana Point reported severe erosion and sand loss after early-September swells from Hurricane Marie, leading to local emergency declarations.
Verbatim Quotes
- “Sea levels are going to be noticeably higher than usual,” — Daniel Swain, UC climate scientist
- “I think people are taking it pretty seriously,” — Ted Hollister
- “Now they know what to prepare for,” — Tammy McGraw, Long Beach
What’s Next
Scientists expect two to three additional Kelvin waves this winter, each capable of adding several inches to coastal water levels. The Climate Prediction Center projects a greater than 90 % chance of a very strong El Niño persisting through the fall and winter, with a 75 % chance it will exceed the strength of any El Niño recorded since 1950. The NWS forecasts continued high-surf advisories through early October and warns that future storms will encounter an already elevated sea surface, heightening the likelihood of coastal flooding and accelerated erosion. Local agencies remain on standby to issue further sandbag distributions, emergency repairs, and public-safety alerts.