The abnormally strong event may boost extreme weather, flooding and erosion of the coast. Few states are more sensitive to what’s happening in the Pacific Ocean than California — and what’s happening in the Pacific this year has no modern precedent.

Because of that, California is expected to face a much higher risk than normal for powerful, moisture-laden storms late this fall and winter, especially from December onward, driven in part by a record-breaking El Niño that resulted in a statewide emergency declaration last month.

Storms, high tides and potentially unparalleled sea levels could raise the chances of coastal and inland flooding and chip away at the beach. The fallout could be a stark reminder of the longer-term challenges facing communities on an eroding shore.

California is no stranger to weather extremes. Over the last 130 years, two California water years stand above the rest: 1982-83 and 1997-98. Both coincided with super El Niño events, similar to the one unfolding now. El Niño is a natural warming of the tropical Pacific Ocean that occurs every two to seven years.

This year’s strong event is anything but typical — and it could have serious consequences across the United States spanning places like beach towns and the Sierra Nevada mountains.

El Niño could amplify coastal flooding Communities along the shore are preparing for an El Niño-fueled “coastally trapped wave” — a bulge in the ocean surface that is expected to raise California’s sea levels by up to a foot in October The trapped wave, on its own, is not destructive, experts said. It won’t come crashing onto the beach like a tsunami. But the higher sea levels it brings could become damaging when combined with high tides and storms.

This week, Hurricane Rachel, despite tracking almost 1,000 miles away from Southern California, could cause minor coastal flooding, beach erosion and dangerous rip currents. Tides of up to seven feet are predicted in coastal parts of Orange and San Diego Counties, where an alert is in effect.

The combination of elevated sea levels and high tides could become especially important this winter. If an extra-high “king tide” coincides with a coastal storm, the effects could compound and be severe. Here’s when these highest tides are expected: Nov. 24-26, 2026 Dec. 22-25, 2026 Jan. 20-23, 2027 But “those waves also cause damage,” he emphasized. “They cause erosion.”Early in September, Hurricane Marie brought big waves that overwhelmed seawalls, destroyed beachfront homes and ate away at the coastline.

In Santa Monica, a music festival was canceled because of beach erosion. In Malibu, a sinkhole at the house of actor Nicolas Cage led dozens of households to evacuate.

The stage is set for destructive storms El Niño could also contribute to more intense storms that bring inland flooding.

atmospheric river is like a river in the sky. These long, narrow plumes of water vapor can transport more water than the world’s mightiest rivers. When that moisture gets squeezed out of the sky by a storm or front, heavy rain can fall. They can bring beneficial increases in snowpack, but they can also produce destructive flooding.

The most hazardous ones tend to occur from January to March. They can form as early as October — though none are expected in the weeks ahead.

big atmospheric river were to occur this winter, the conditions leading up to it could make a difference. A stormier El Niño pattern, for instance, could leave the soil wet and “primed” for flooding, said Ralph.

Much warmer Pacific waters could also provide extra energy to storms approaching California.

During the powerful 1997-98 El Niño, Ralph said, research flights found that coastal waters about 2 degrees Celsius (3.6 degrees Fahrenheit) warmer than normal increased the energy of thunderstorms that struck the Santa Barbara area by roughly 25 percent. That contributed to 3-inch-per-hour rainfall and river flooding.

“I think we do need to keep our eyes open for an exceptionally big event this winter because all that heat in the ocean does help energize the storms,” said Ralph.

Because of the expected abundance of moisture, McCarthy anticipates mountain areas above 7,000 or 8,000 feet will get pummeled by snow this winter. However, because of warmer temperatures, resort base areas around 6,000 feet could instead see more rain and less snow.

If a warm atmospheric river drops heavy rain onto saturated soils and a deep snowpack, then melting snow could also add to potential flooding. What happens in California could reverberate around the U.S.

Storms that move from the Pacific into California sometimes begin a cross-country journey. Their energy can even help fuel storms along the East Coast. How are people preparing?

California Gov. Gavin Newsom declared a statewide emergency over El Niño last month, directing officials to prepare before it reaches peak intensity later in the year. Authorities say they are staging equipment such as sandbags and pumps around the state ahead of time.

The specific effects depend on when and where stormy weather develops, officials said. Coastal communities should be especially on guard for king tides expected in November and December, they said, even if no storms materialize.

Officials have declared emergencies in coastal cities including Laguna Beach. Waves there damaged the seawalls that protect oceanfront homes and washed away sand underneath a sidewalk and parking lot at a popular beach.

The threat to beachfront homes has resurfaced long-running tensions over how to protect the private properties most vulnerable to big waves. Some homeowners want to build rock walls and other fortifications to help keep the water at bay, but California tightly restricts those projects over concerns that they can increase erosion and hurt public beaches in the long run.

In Dana Point — where storms destroyed beachfront homes last month — residents got emergency permits to build a wall, but they have to take it down after 120 days unless they get permanent approval.

In the longer term, many officials and residents are pushing for more projects to replace lost sand.