Experts are raising the alarm about El Niño, a climatic phenomenon anticipated to develop this summer, which could lead to widespread flooding even in the absence of storms.
According to the National Oceanic and Atmospheric Administration (NOAA), the factors contributing to this risk have been accumulating over several years. This federal agency is tasked with monitoring weather and climate patterns.
“It usually ends up being a double whammy,” explained William Sweet, an oceanographer at NOAA. “The first issue is the decades-long sea level rise, which has brought water levels alarmingly close to the edge in many coastal areas. Now, with the added impact of a strong El Niño, coastal regions are likely to experience more frequent and severe high tide flooding along both the West and East Coasts.”
Sweet’s expertise lies in “high tide flooding,” an increasingly prevalent issue that leaves coastal areas vulnerable to flooding as sea levels continue to rise.
El Niño is part of the El Niño-Southern Oscillation (ENSO) cycle, a weather pattern that alternates every two to seven years, according to NOAA. The cycle is currently neutral, having shifted from its cooler phase, La Niña, earlier this year.
Forecasters anticipate that El Niño, the warmer phase of the ENSO cycle, will soon make its appearance. The NOAA Climate Prediction Center reported last week that there is at least an 82% chance it will materialize by July and persist through February in the Northern Hemisphere.
El Niño also causes trade winds to weaken across the tropical Pacific Ocean, setting off a chain of events that ultimately warm the ocean and raise sea levels around the Americas, typically for at least several months, according to NOAA. During this phase of the cycle, the west coast of the U.S. may see high tides and strong surf, while the Atlantic coast may experience more storm surge and the southeastern and Gulf coasts could receive excessive rain.
Scientists are still working out just how intense the upcoming El Niño will be. Sweet said the El Niños that prevailed from 2015 to 2016 and 2023 to 2024 were particularly strong and resulted in upticks in high tide flooding compared with previous years, which is something NOAA has been tracking and trying to better understand.
NOAA has encouraged communities along any U.S. coast to stay informed using the agency’s coastal inundation dashboard, which is updated with current water levels and forecasts, in addition to its monthly flooding outlooks.
