Predicting the weather is always difficult, and even the most solid forecasts sometimes fall short of expectations.
But in recent months, the world's weather experts have become more united in believing that we were going to be hit by a new El Niño weather pattern, and the consensus of computer models suggests it will likely be a very strong one.
California is no stranger to the effects of El Niño, with the pattern associated with some of the state's most memorable destructive winter seasons.
Scientists continue to monitor conditions in the Pacific Ocean, offering indications of how El Niño is progressing. But here's a look at where we currently stand with respect to the forecast:
What do the latest models show?
The National Oceanic and Atmospheric Administration's Climate Prediction Center said Thursday that there is a 97% chance that El Niño will be “strong” or “very strong” over a three-month period ending in December. There is an 81% chance that it is “very strong.”
Colloquially, the “very strong” El Niño has been called the “super” El Niño.
Officials warn that the weather pattern, characterized by warmer waters in the central and eastern tropical Pacific Ocean, will also increase the risk of heat waves on land and sea, which are already being exacerbated by human-caused global warming.
Last month, authorities declared the arrival of El Niño, which typically lasts nine to 12 months. It will take time for the weather pattern to accelerate.
What exactly is El Niño?
El Niño is a pattern that typically arises every two to seven years and lasts nine to 12 months, according to NOAA.
The climate pattern is marked by the combination of warmer water in the central and eastern tropical Pacific Ocean along with changing conditions in the atmosphere, in which the typical east-west trade winds along the equator weaken or even reverse.
When the east-west trade winds weaken, sea level rises a little in the western Pacific and creates what's called a descending oceanic Kelvin wave, said Jon Gottschalck, head of the Climate Prediction Center's operational forecasting branch. “Basically, it's a wave in the ocean that will bring warm water from the western Pacific to the central and eastern Pacific.”
When the temperature difference decreases between the warmer western Pacific and the colder eastern Pacific, the typical east-west trade winds decrease further. That creates a positive feedback loop: Weaker winds generate more warm water moving east, weakening the winds even further.
What are the potential impacts?
El Niño usually causes different climate impacts around the world, depending on the season.
As warm water spreads off the coasts of Mexico, Central America and northern South America during El Niño, the energy of the jets in the atmosphere generally brings stormier-than-usual weather to the southern United States, including southern California, Texas and Florida, during the winter, said Ariel Cohen, a meteorologist with the National Weather Service in Oxnard.
According to Cohen, this also typically brings drier than normal conditions further north, such as the Pacific Northwest.
Around the world, El Niño typically brings Australia and northern South America very dry conditions and can cause droughts, Cohen said. Meanwhile, wetter conditions are likely to prevail in eastern Africa.
“There's really a wide range of impacts that can occur that vary significantly from place to place around the world,” Cohen said.
El Niño also increases the risk of heat waves on land and sea, which are already being exacerbated by human-caused global warming.
“We know that temperatures are rising over the long term, due to human-caused climate change, and El Niño acts to temporarily raise those temperatures,” said climatologist Zachary Labe of the nonprofit Climate Central. “This would indicate a very high probability that we will break new global temperature records in just a few months.”
What could Southern California expect?
For Southern California, it would mean a higher chance of above-average precipitation, with the risk of a winter of flash flooding and mudslides.
During three of the four “very strong” El Niños in the world record, downtown Los Angeles received significantly more rain than average. In two years (1982-83 and 1997-98), downtown Los Angeles received more than double its usual annual rainfall.
But the connection is not absolute. During the last “very strong” El Niño in 2015-16, the center received only half of its typical annual precipitation.
The last El Niño, in 2023-24, was “strong.” For the water year ending September 30, 2024, downtown Los Angeles received 22.15 inches of rain, or 155% of the average annual precipitation of 14.25 inches. That winter brought hundreds of landslides in Los Angeles and the second wettest three-day period in downtown Los Angeles since records began in 1877.
There was also well above average rainfall on the Southern California coast and slightly above normal rainfall on the Northern California coast, the state Department of Conservation said.
But not all of California received the abundance of precipitation during that El Niño. Below-normal rainfall occurred in inland areas such as the Sierra Nevada and the deserts of southeastern California.
More flooding during high tide is also possible in the event of an El Niño. The “very strong” El Niño of 2015-16 caused “record coastal erosion on many California beaches,” the state Coastal Commission said.
This year's El Niño is also expected to prolong an already existing marine heat wave (currently in effect for reasons unrelated to El Niño) off the coast of Southern California.
A marine heat wave in the ocean off the coast of Southern California and further west in Northern California and Oregon.
What about warming ocean waters?
Scientists are sounding the alarm about the warming of the planet's oceans. El Niño typically increases global temperatures, the World Meteorological Organization said, and high sea surface temperatures can “intensify heat extremes in nearby land areas.”
“An El Niño event is a source of heat to the atmosphere, raising global temperatures and changing weather patterns around the world,” the World Meteorological Organization said.
On July 1, officials confirmed that global sea surface temperatures in June hit a record high for this time of year.
“Current conditions could signal the beginning of a new phase, which would lead, once again, into uncharted territory. With ocean temperatures at these levels and El Niño on the horizon, we are likely to see more record temperatures fall in the coming months,” said Carlo Buontempo, director of the Copernicus Climate Change Service, an arm of the European Union.
Warming ocean waters have wide-ranging effects, scientists say. They can provide additional energy to storms and increase evaporation, increasing the possibility of extreme precipitation and flooding; contribute to sea level rise; exacerbate melting ice and stress marine ecosystems, according to a statement from the Copernicus Climate Change Service and the Copernicus Marine Service.
