Archive · 28 Sep 2026
Strengthening El Niño Threatens California With Flooding and Erosion
El Niño is a weather pattern that warms parts of the Pacific Ocean.
It can make storms and strong winds more powerful.
California has already seen beaches shrink and some coastal homes damaged.
Scientists say underwater Kelvin waves could raise sea levels near the coast.
Higher seas could make flooding worse when large storms arrive.
Experts estimate that floods and mudslides could cause billions of dollars in damage this winter.
Areas near old wildfire burn scars may be especially likely to experience mudslides and flash floods.
California officials are inspecting roads, bridges, levees, and other vulnerable structures.
Some communities are also teaching residents how to prepare for dangerous storms.
El Niño could cause an estimated $2 billion to $3 billion in California flood and mudslide losses through winter.
Kelvin waves may raise Pacific sea levels and worsen coastal flooding when storms hit California.
Storm remnants already caused severe beach erosion and damaged more than a dozen Orange County homes.
Climate X estimates coastal erosion risk rises by more than two-thirds during extreme El Niño events.
Governor Gavin Newsom declared a statewide emergency as communities prepare for stronger winter storms.
- Who
- California communities and state agencies, scientists, and Governor Gavin Newsom are responding to the El Niño threat.
- What
- A strengthening El Niño is increasing the risk of coastal erosion, flooding, mudslides, and infrastructure damage.
- When
- El Niño developed in June; a significant Kelvin wave is expected by early October, with the heaviest rains expected during winter.
- Where
- The risks affect California’s coastline and vulnerable inland areas, including Orange County, Malibu, Carlsbad, and areas near wildfire burn scars.
- Why
- El Niño can intensify Pacific storms, heavy surf, atmospheric rivers, and sea-level-raising Kelvin waves.
- Estimated statewide losses
- Climate X estimates $2 billion to $3 billion in flood and mudslide losses through winter.
- Typical annual flood damage
- California averages about $500 million in flood damages annually, according to Climate Central.
- Kelvin wave sea-level increase
- Recent Kelvin waves have raised sea levels by up to 16 inches, or 40 centimeters, across the Pacific.
- Recent coastal damage
- Storm remnants in early September severely damaged more than a dozen oceanfront homes in Orange County; at least one was marked for demolition.
- Emergency declaration
- Governor Gavin Newsom declared a statewide emergency on September 22.
- Expected next wave
- A significant Kelvin wave is expected to reach California by early October.
- Highest-risk areas
- Coasts, wildfire burn scars, slopes, vulnerable canyons, roads, bridges, levees, and channels face elevated risks.