Prepare for extreme weather events including intense heat, drought, and flooding—it’s officially El Niño season. The National Weather Service reported on Thursday.
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NWS models indicate this El Niño event could rank among the most powerful recorded.
“There is a 63% likelihood of a very strong El Niño from November to January, potentially marking one of the largest events in history,” said Ariel Cohen, meteorologist with the NWS in Los Angeles, during a press conference at the Aquarium of the Pacific in Long Beach, California. “We are already witnessing sustained warm temperatures.”
El Niño is a natural climate phenomenon that leads to elevated surface temperatures in the tropical Pacific. This increase is linked with a rise in global average temperatures, exacerbating climate change impacts. Typically, it is associated with fewer hurricanes in the Atlantic and increased hurricane activity in the Pacific.
In the U.S., El Niño’s effects peak in winter, altering the usual jet stream flow that influences Northern Hemisphere weather patterns, pushing the jet stream southward.
This year, the Pacific Northwest faces drought conditions following a dry winter with lower snowfall. Conversely, southern states may experience unusually wet winters, leading to flooding.
El Niño can trigger powerful ocean heatwaves, disrupting marine ecosystems and causing mass fish mortality, along with bringing tropical fish species into coastal areas.
Andrew Rising, research oceanographer at NOAA’s Southwest Fisheries Science Center, noted that two marine heatwaves have already impacted the Pacific. One is near California’s coastline, while another is occurring offshore.
Though not directly caused by El Niño, NOAA models indicate that ocean temperatures in the Pacific are expected to rise more rapidly this fall, intensifying ongoing heatwaves, according to Liesing.
“For marine life, the duration of heat exposure is critical,” Rising explained. “After a previous heat wave in Southern California, we’re about to face another due to El Niño.”
Past prolonged marine heatwaves have reduced plankton, essential to the food web, leading to harmful algae blooms that produce neurotoxins detrimental to marine life and increasing whale entanglements as they come closer to shore.
Rising highlighted that while some species might thrive during heatwaves, such as jellyfish and certain rockfish, many others face dire consequences.
In 2015, an exceptional marine heatwave known as “the Blob” caused ocean temperatures to soar by approximately 7°F, severely impacting marine ecosystems. Sea lions, seals, baleen whales, and seabirds perished due to food scarcity and increased algal toxins, according to Liesing.
The Blob significantly disrupted fisheries worth millions on the West Coast, leading to instances of Pyrosome proliferation—a jelly-like organism clogging fishing nets.
Rising noted that the back-to-back heatwaves experienced in 2015 were more severe than those anticipated this year.
Another indicator of El Niño may involve unusual fish sightings along the West Coast.
“These events may attract unique visitors,” explained Nate Jarosz, vice president of animal care at the Aquarium of the Pacific. Historical El Niño events have introduced rare species to the California coast, including yellowfin tuna, dolphinfish, and whale sharks.
Shark sightings tend to spike in Southern California during previous heatwaves.
“Warmer waters appeal to shark species such as mako and great white sharks, potentially shifting their ranges further north,” Jarosz added. “During past heatwaves, coastal species, including blues and macaws, have dense populations along the West Coast.”
El Niño typically contributes to rising global temperatures, with climate change as the primary driver behind recent record warmth. The hottest year documented was 2024, with temperatures approximately 2.65°F (1.47°C) above the mid-19th century average, according to NASA. Scientists noted that the El Niño pattern raised temperatures that year, while 2025 recorded as the third warmest year despite the cooling influence of La Niña. (La Niña is the opposite of El Niño.) The past 11 years represent the hottest years on record globally.
Source: www.nbcnews.com
