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What Coastal Homeowners Need to Know

• A massive El Niño-linked Kelvin wave moving toward California could temporarily push coastal water levels higher, magnifying flooding when storms, large surf or king tides arrive.
• California’s 2026–27 king tides begin November 24–26, creating several periods when already elevated ocean levels could combine with unusually high astronomical tides.
• A huge insurance trap exists—standard homeowners insurance generally does not cover flooding from the ocean, regardless of whether El Niño, a Kelvin wave or a king tide helped cause it.

By Samuel López | USA Herald

MONTEREY - California’s next major coastal insurance problem may arrive before the biggest winter storm does.

Scientists are watching a large El Niño-related Kelvin wave moving along the Pacific toward California, a phenomenon capable of temporarily pushing coastal sea levels higher for an extended period. NOAA says coastally trapped Kelvin waves were a signature of the powerful 1997–98 El Niño and researchers are watching for similar waves along the West Coast this fall.

Here’s the simplest way to picture it.

Imagine a bathtub filled slightly higher at one end because a powerful fan has been blowing the water in that direction. Now turn off the fan. The piled-up water does not disappear—it sloshes back across the tub.

On the Pacific, the “fan” is the trade winds. During El Niño, those winds weaken, allowing a huge mass of warm western Pacific water to move eastward. Once that elevated water reaches the Americas, geography prevents it from simply continuing east. Part of that energy and elevated sea level moves north and south along the coast.

That is a Kelvin wave.

It is not a thousand-mile-wide version of a breaking beach wave crashing into California all at once. It is an enormous, slow-moving pulse of ocean water and energy. Scientists say the present event could temporarily raise water levels along portions of the California coast by as much as roughly a foot.

Now add into the mix, King Tides.

The California Coastal Commission lists statewide king-tide periods for November 24–26 and December 23–25, 2026, followed by January 21–22, 2027. King tides are simply the highest predicted astronomical tides of the year—but the Commission warns that this winter’s strong El Niño and Kelvin waves could cause actual water levels to exceed predicted tide heights.

That combination matters in places like Monterey, where coastal flooding and wave run-up are already recognized hazards. City planning documents identify the Recreation Trail and Del Monte Avenue among areas vulnerable to coastal flooding and recognize erosion and storm-wave exposure as continuing concerns along Monterey Bay.

Governor Gavin Newsom declared a state of emergency on September 21 to accelerate statewide El Niño preparations, mobilize resources and allow California to respond more quickly before potentially severe winter conditions intensify.

For homeowners, however, government preparation solves only part of the problem.

Insurance coverage depends less on what meteorologists call the event than on what actually damaged the property.

A Kelvin wave is not itself an insurance coverage category. Neither is El Niño or a king tide.

If elevated ocean water inundates normally dry land, the claim may fall within the definition of flooding, including overflow of tidal waters. California’s Department of Insurance warns that standard homeowners and commercial property policies typically exclude flood damage. Separate flood insurance through the National Flood Insurance Program or a private carrier may cover qualifying direct physical flood losses.

There are important distinctions.

Wind-driven rain entering a damaged structure may be covered under some homeowners policies. Damage from a fallen tree is generally covered. But water moving inland from the ocean, coastal flooding, gradual erosion, landslides and certain forms of earth movement can trigger exclusions or entirely different coverage rules. California regulators specifically list flood, earth movement and tidal-wave losses among perils generally excluded from standard homeowners policies.

That is where this winter could become difficult for insurers and policyholders alike.

Catastrophe models can estimate storm frequency, rainfall, elevation, flood zones and historical losses. But compound events are harder - elevated baseline sea levels, a Kelvin wave, king tides, large surf, storm surge and heavy rainfall can arrive together. The damage seen at one house may involve several causes operating almost simultaneously.

For an insurer, identifying the cause determines which policy responds.

For a homeowner standing in six inches of seawater, that distinction can determine whether there is coverage at all.

California Insurance Commissioner Ricardo Lara has already urged residents to review their policies and consider flood protection before what state officials describe as a potentially historic El Niño season.

The practical lesson is not to wait until the ocean is coming over the road. Coastal homeowners—including residents around Monterey Bay—should know now whether they have separate flood coverage, what their homeowners policy excludes, and how erosion, tidal flooding and storm-driven water are treated.

The Kelvin wave may raise the water.

A king tide may raise it further.

But when that water reaches somebody’s living room, the wording inside the insurance policy becomes just as important as the forecast.

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