Scientists are now estimating the Kelvin Wave sea rise at 1/2 foot.
A slow-moving oceanic phenomenon known as a Kelvin wave is heading toward the California coast and could raise sea levels there by as much as a foot, according to reporting from The Guardian. Scientists say the wave, a planetary-scale surge of warm water thousands of miles across, forms when Pacific trade winds weaken or reverse during El Niño years, sending water that normally piles up near Asia sloshing back toward the Americas. NASA researcher Severine Fournier explained that the wave travels along the equator before splitting north and south once it reaches South America, with one such wave now advancing up the West Coast and expected to reach California within days.
NOAA scientist Nate Mantua noted the phenomenon is a natural, centuries-old occurrence, but stressed it will now stack on top of roughly eight inches of sea-level rise already recorded over the past century. This year’s El Niño is shaping up to be one of the strongest on record, and researchers warn its effects — including elevated tides, stronger storms, and increased flooding risk — could compound each other, particularly if storms coincide with seasonal high tides expected around Thanksgiving and Christmas.
In response, California Governor Gavin Newsom has declared a state of emergency to pre-position resources such as road-clearing equipment and National Guard support ahead of possible winter storms. The California Coastal Commission has also urged residents in flood- or erosion-prone areas to prepare in advance, with the commission’s director warning that storms arriving during high tide tend to cause substantially more damage than those hitting at low tide.
Source: The Guardian, reporting by Nick Visser, Sept. 28, 2026.