El Niño Intensifies: Impacts on Major U.S. Cities Expected This Winter
Major U.S. cities like Los Angeles and Atlanta should prepare for heavier rainfall, potential flooding, and other significant weather changes this winter. This is due to the strengthening of the El Niño phenomenon, as noted by AccuWeather’s lead long-range expert, Paul Pastelok, in a conversation with Newsweek.
Understanding El Niño
El Niño represents the warm phase of the El Niño-Southern Oscillation (ENSO), a Pacific climate pattern affecting global weather. Its opposite, La Niña, is the cool phase. Typical effects of El Niño include increased storm activity in the South, drier conditions in some northern regions, and altered hurricane patterns.
Historically, strong El Niño events have coincided with extreme weather. For example, the 1997-98 Super El Niño led to severe flooding in California and Peru. The 2015-16 El Niño was linked to record global temperatures and widespread climate disruptions.
Cities Facing Significant Weather Changes
Pastelok highlights that cities such as Los Angeles, San Francisco, Houston, and Atlanta are likely to experience increased rainfall and potential flooding. These areas are often impacted by a southern storm track during robust El Niño conditions, especially in late fall and winter. California, in particular, faces risks such as landslides due to its topography.
Additionally, river levels along the Mississippi, Tennessee Valley, and the Carolinas may rise rapidly, affecting nearby cities. Pastelok also mentions that the East Coast could see strong storms, coastal flooding, and high winds impacting cities like Norfolk, Atlantic City, and Boston.
Insights from NOAA’s Winter Outlook
The National Oceanic and Atmospheric Administration’s (NOAA) Climate Prediction Center (CPC) released maps showing temperature and precipitation outlooks for December 2026 through February 2027. These projections favor above-normal temperatures across many regions, including the Pacific Northwest, northern Rockies, Midwest, and Northeast. The strongest warming signal appears in the northern tier.
While above-normal temperatures are likely in much of the South, the forecast is less clear for parts of California and the Southwest. Precipitation maps show wetter-than-normal conditions expected from Southern California through the Southwest, southern Plains, Gulf Coast, Florida, and parts of the East Coast.
In a recent update, the CPC stated there is a 75% chance that El Niño will reach historic strength during October to December, surpassing past records dating back to 1950. This probability has risen from 69% since the agency’s August update. Although such a strong event increases the likelihood of typical El Niño impacts, these effects are not certain.