Map Shows States Most Exposed to El Niño Flood Risk

An impending "historic" El Niño weather event could heighten flood risks in various sections of the United States over the forthcoming months, according to meteorological experts. Forecasts indicate the most significant increase in flood risk is anticipated in California and the southern portion of the U.S., with the threat expected to peak during the winter months.

El Niño is a cyclical climate phenomenon characterized by warmer Pacific waters, which impacts global temperatures and precipitation patterns. Currently, this ongoing El Niño has shattered records and is anticipated to intensify further by the end of the year, potentially reaching unprecedented levels during October to December.

Heather Zons, a meteorologist and principal weather producer at The Weather Channel, explained that El Niño enhances the subtropical jet stream, leading to above-average rainfall across Southern California and Florida. She identified the Southwest and South Florida as regions of concern from January through March. Arizona and New Mexico may face heightened vulnerability due to the region's mountainous terrain, canyons, and steep slopes, which can rapidly direct water into communities and roads.

Zons warned that "rushing water could easily overwhelm dry washes, significantly impacting neighborhoods and roads," and that the sandy soil prevalent in these areas may struggle to absorb excess rainfall, especially as development encroaches upon them. This, in turn, amplifies the likelihood of nuisance flooding. Fox Weather meteorologists Ian Oliver and Greg Diamond echoed similar concerns, pinpointing California and the southern U.S. as regions where a stronger-than-normal southern branch of the jet stream could generate more storm systems, increasing the threat of heavy rainfall and severe thunderstorms.

They also noted that the pattern could elevate the potential for flooding and severe weather in the Southeast, with conditions already emerging in the fall and expected to intensify during the winter. "With the impending strength of this El Niño, this winter could witness a series of high-impact weather events," the meteorologists stated.

Jane Minar, another Fox weather meteorologist, noted that California and coastal states along the Gulf often experience heightened flood risks during El Niño winters. "There is an indication that January and February could bring a wetter pattern, which would exacerbate flood potential for Florida, the Carolinas, as well as California," Minar stated.

Zons also highlighted the Great Lakes and Ohio Valley as areas to monitor, given previous periods of heavy rainfall. She suggested that milder El Niño conditions could result in a larger share of winter precipitation falling as rain instead of snow.