Giant Pacific Wave Approaches US Coast, Threatening 'Quintuple Whammy' Flooding

A massive wave originating in the Pacific Ocean is on track to strike the U.S. West Coast in the coming days, bringing with it the potential for severe flooding and threatening coastal communities. Oceanographers have identified multiple Kelvin waves moving northward, with the next significant wave anticipated to reach San Diego by late October or early November.

One such wave is believed to have contributed to coastal flooding and evacuations in California earlier this month during Tropical Storm Rachel. Kelvin waves are planetary-scale phenomena characterized by warm ocean water that form when tropical winds weaken during El Niño conditions. This weakening allows warm water, typically concentrated in the western Pacific, to surge eastward across the equator, impacting South America before moving up the coast toward the United States. The result can be a temporary but dramatic increase in sea levels, potentially by as much as a foot.

The National Oceanic and Atmospheric Administration (NOAA) has cautioned that California could face a "quintuple whammy" this year. This confluence of factors includes warmer ocean temperatures, the passage of tropical storms, unusually high tides, the arrival of Kelvin waves, and the overarching influence of climate change. These elements are expected to collectively elevate sea levels and put thousands of coastal residents at risk.

According to NOAA, one or two additional Kelvin waves are still within the tropics. During a strong El Niño year, which can cause global weather patterns to shift due to abnormally warm ocean temperatures, it is not uncommon for five or six Kelvin waves to traverse the Pacific. The current El Niño event, which emerged this summer, has the potential to be a record-breaker, with Pacific temperatures predicted to rise significantly.

Oceanographer Dillon Amaya noted that the Kelvin wave impacting the West Coast in early October 2026 is thought to have intensified the flooding caused by Tropical Storm Rachel. This event led to flooded streets and homes in areas like the Long Beach Peninsula and Newport Beach's Balboa Peninsula, with some homes in Long Beach being marked as unsafe. Similar flooding and erosion were observed in the San Diego area.

"That storm surge was almost certainly made more devastating because of the Kelvin wave," Amaya stated in a recent interview. NOAA further explained that while a Kelvin wave alone might add six to 12 inches to sea levels, its effects can be significantly amplified when combined with high tides or storm surges, as the sea level is already elevated.

These Kelvin waves, described as thousands of miles across, first impact the northern coast of South America before ricocheting northward along the coasts of Mexico and then the U.S. Climate scientist Mark Cane likened the phenomenon during El Niño years to an "enormous bathtub" sloshing, with the wave's eastward movement along the equator being a peculiar characteristic.

Forecasters at AccuWeather have warned that the potentially record-breaking warmth in the Pacific could extend the effects of El Niño well into 2027, influencing climate patterns throughout the year. The upcoming Kelvin waves are expected to continue arriving along the West Coast through the fall and early winter, typically fading before the peak of an El Niño event in early January. The warming waters in the Pacific also create conditions favorable for the formation of more tropical storms and hurricanes, while the weakening of trade winds allows the warm water to be transported eastward.

This shift in the jet stream, driven by warmer Pacific temperatures, is also projected to push moisture and storms further south across the United States, potentially bringing unusual winter weather to many southern states.