Meteorologists say we should prepare for an El Niño winter in 2023-2024 due to late summer water temperatures. El Niño and La Niña are climate patterns in the Pacific Ocean that can affect weather worldwide, and that can last nine to 12 months, or even years. Weather events occur every two to seven years, but not on a regular schedule, and El Niño is more common than La Niña. 

 According to the National Oceanic and Atmospheric Administration (NOAA), during normal Pacific Ocean conditions, trade winds blow west along the equator, moving warm water from South America toward Asia, and cold water rises to replace that warm water. During El Niño, trade winds weaken, and warm water is pushed east toward the west coast.  

 South American fishermen discovered El Niño in the 1600s, naming it “El Niño de Navidad” because it typically peaks around December. During an El Niño, areas in the northern United States and Canada are dryer and warmer than usual, but the Gulf Coast and Southeast experience wetter conditions with more flooding.

La Niña has the opposite effect, with stronger trade winds pushing warm water towards Asia, and cold waters in the Pacific pushing the jet stream northward. This causes drought in the southern U.S. and heavy rains and flooding in the Pacific Northwest and Canada. During a La Niña year, winter temperatures are warmer than normal in the South and cooler than normal in the North.  

Strong El Niños produce warm signals across the Lower 48, while more moderate events can cause warmth or extreme cold. Weaker El Niños often produce the coldest winters. There hasn’t been an El Niño since the 2018-19 season, but change, while difficult to predict, is coming.