Prepare for extreme heat, drought, and flooding as it’s officially El Niño season. The National Weather Service announced on Thursday.
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According to NWS models, the current El Niño event may rival the most intense events ever documented.
“There is a 63% likelihood of a very strong El Niño occurring from November through January, potentially ranking it among the largest events in history,” stated Ariel Cohen, a meteorologist with the NWS in Los Angeles, during a press conference at the Aquarium of the Pacific in Long Beach, California. “We’re already experiencing persistently warm temperatures.”
El Niño is a natural climate phenomenon that leads to elevated surface temperatures in the tropical Pacific Ocean. This is linked to a rise in global average temperatures, intensifying the warming attributed to climate change. The phenomenon is also correlated with fewer hurricanes in the Atlantic while increasing their frequency in the Pacific.
In the United States, the effects of El Niño are most noticeable during winter, as it alters the typical jet stream flow encircling the Northern Hemisphere, thereby shaping weather patterns. This pattern usually drives the jet stream further south.
This year, there’s considerable concern in the Pacific Northwest, which is already facing drought conditions after a dry winter that left much of the region with below-average snowfall. Conversely, southern states can expect significantly wetter winters that may lead to flooding.
El Niño can also induce severe ocean heatwaves, disturbing marine ecosystems and leading to mass fatalities among marine life, along with the influx of rare tropical species into coastal waters.
Andrew Rising, a research oceanographer at NOAA’s Southwest Fisheries Science Center, noted that two marine heatwaves are currently impacting the Pacific Ocean—one near California’s coast and another further out at sea.
While El Niño is not the direct cause of these phenomena, NOAA projections indicate that the pattern will accelerate Pacific Ocean temperature increases this fall, subjecting various regions to consecutive heatwaves, according to Liesing.
“One crucial factor for wildlife in an ecosystem is not merely the intensity of heat, but also the duration of exposure,” Rising emphasized. “We’ve recently witnessed a heatwave in Southern California, and we are about to experience another one associated with El Niño.”
He further explained that prolonged marine heatwaves can diminish plankton populations at the food chain’s base, triggering harmful algal blooms that produce neurotoxins detrimental to marine animals. There has also been a rise in whale entanglements, as whales increasingly venture closer to shore, thereby heightening the risk of interaction with boats and fishing gear.
According to Rising, some species benefit from marine heatwaves. “The jellyfish population is surging, and more rockfish are transitioning from larvae to juveniles.”
Unfortunately, these changes are detrimental to many species.
In 2015, a unique marine heatwave termed the “Blob” raised ocean temperatures by approximately 7 degrees Fahrenheit above average, resulting in widespread devastation to marine life. Seals, sea lions, baleen whales, and seabirds perished, likely due to food shortages and increased toxins from algal blooms, according to Liesing.
The Blob also severely disrupted millions of dollars worth of Dungeness crab, sea urchin, and salmon fisheries along the West Coast, leading to incidents like pyrosome proliferation, where jellyfish-like creatures congested fishing nets.
However, Rising noted that the intensity of the heatwaves seen in 2015 surpasses those expected this year.
Another potential indicator of El Niño is the presence of unusual fish along the West Coast.
“This may lead to some unexpected visitors,” said 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, seahorses, and whale sharks.
Shark sightings have increased in Southern California during previous ocean heatwaves.
“Warmer waters attract certain shark species, including mako, blue, and great white sharks, which may lead to expanded ranges for many species further north,” Jarosz explained. “In past heatwaves, coastal species like blues and macaws flourished in high densities along the West Coast.”
Overall, El Niño tends to raise global temperatures, with climate change remaining a primary contributor to the recent record warmth. The hottest year so far was 2024, with temperatures approximately 2.65 degrees Fahrenheit (1.47 degrees Celsius) above the mid-19th century average, according to NASA. Scientists have indicated that the El Niño pattern elevated temperatures that year, while 2025, marked as the third hottest year on record, experienced a La Niña phase, which typically cools temperatures. (La Niña is the antithesis of El Niño.) Notably, the last 11 years have comprised the hottest years recorded globally.
Source: www.nbcnews.com