Weather forecasting is always tricky, and even the strongest forecasts sometimes don’t live up to the hype.
But in the last few months, the world’s climate experts have become more and more united in the belief that we will be hit by a new El Niño climate, and the consensus of computer models shows that it will probably be very strong.
California is familiar with the effects of El Niño, a pattern associated with the region’s other devastating winters.
Scientists continue to monitor conditions in the Pacific Ocean, which gives clues as to how El Niño is progressing. But here’s a look at where we stand now with the forecast:
What do the latest models show?
The National Oceanic and Atmospheric Administration’s Climate Prediction Center on Thursday said there is a 97% chance that El Niño will be “strong” or “very strong” in the three-month period ending this December. There is an 81% chance that it will be “very strong.”
Colloquially, the “strongest” El Niños have been called “high” El Niños.
Officials warn that the weather – characterized by warmer waters in the central and eastern tropical Pacific Ocean – will also increase the risk of heat waves on land and at sea, which are already being exacerbated by human-caused global warming.
Authorities last month announced the arrival of El Niño, which usually lasts nine to 12 months. It will take time for the weather pattern to recover.
What exactly is El Niño?
El Niño is a pattern that usually occurs every two to seven years, and lasts for nine to 12 months, according to NOAA.
The weather pattern is marked by a combination of warm waters in the central and eastern tropical Pacific Ocean associated with changing atmospheric conditions, where the normal east-to-west trade winds near the equator weaken or retreat.
When the east-to-west trade winds weaken, sea levels rise slightly in the western Pacific and create a so-called Kelvin wave, said Jon Gottschalck, chief of the Climate Prediction Center’s operational forecasting branch. “Essentially, ocean currents will bring warm water from the western Pacific to the central and eastern Pacific.”
If the temperature difference decreases between the warmer western Pacific and the cooler eastern Pacific, the normal east-to-west trade winds decrease even more. That creates a positive feedback loop – weaker winds breed warm water that moves eastward, which weakens the winds even more.
What are the possible impacts?
El Niño usually brings different weather effects around the world, depending on the season.
As warm water passes off the coast of Mexico, Central America and northern South America during El Niño, that causes the jet stream to bring more stormy 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.
That also brings drier-than-normal conditions farther north, such as the Pacific Northwest, according to Cohen.
Globally, El Niño often gives Australia and northern South America very dry conditions, and can cause drought, Cohen said. Meanwhile, wet conditions may prevail in eastern Africa.
“There is a range of potential impacts that vary greatly from place to place around the world,” said Cohen.
El Niño also increases the risk of heat waves on land and at sea, which are already being exacerbated by human-caused global warming.
“We know that temperatures are warming over time, related to human-caused climate change, and El Niño is temporarily boosting those temperatures,” said climate scientist Zachary Labe of the nonprofit Climate Central. “This could indicate that we are very likely to break new global temperature records in just a few months.”
What can Southern California expect?
In Southern California, it could mean a higher chance of above-average rainfall, which poses a risk of winter flooding and landslides.
Among the four “strongest” El Niños on record worldwide, the city of Los Angeles received significantly more rain than average. Both – in 1982-83 and 1997-98 – the city of LA received more than double the normal annual rainfall.
But the connection is not perfect. During the last “very strong” El Niño in 2015-16, the city received only half of its normal annual rainfall.
The last El Niño, in 2023-24, was “strong”. In the water year ending September 30, 2024, the city of LA received 22.15 inches of rain for the city of Los Angeles – that’s 155% of the annual rainfall average of 14.25 inches. That winter brought hundreds of landslides across Los Angeles and the city of LA’s second wettest three-day period since records began in 1877.
There was also above-average rainfall along the Southern California coast and slightly above-normal rainfall along the northern California coast, the Department of Environmental Conservation said.
But not all of California received much rain during that El Niño. There was below normal rainfall in interior areas such as the Sierra Nevada and deserts of southeastern California.
Additional high tide flooding is also possible during El Niño. The “very strong” El Niño of 2015-16 brought “record coastal erosion to many California beaches,” the state Coastal Commission said.
This year’s El Niño is also expected to extend an already existing ocean heat wave — currently operating for reasons unrelated to El Niño — along the Southern California coast.
Ocean heat wave in the ocean off the coast of Southern California and west of Northern California and Oregon.
What about ocean warming?
Scientists are raising the alarm about the warming of the planet’s oceans. El Niño tends to increase global temperatures, the World Meteorological Organization says, and higher ocean temperatures “can increase temperature extremes in nearby areas.”
“The El Niño phenomenon is a source of heat in the atmosphere, which increases global temperatures and changes the global climate,” said the World Meteorological Organization.
On July 1, officials confirmed that global ocean temperatures in June reached a record for this time of year.
“The current conditions may indicate the beginning of a new phase, leading, again, to an unknown place. With sea temperatures at these levels and El Niño on the horizon, we will probably see many temperature records falling in the coming months,” said Carlo Buontempo, director of the Copernicus Climate Change Service, an arm of the European Union.
Warmer ocean waters have a variety of effects, scientists say. They can give more strength to storms and increase evaporation, increasing the chance of heavy rain and flooding; impact on sea level rise; increase the melting of ice and stress the marine environment, according to a statement from the Copernicus Climate Change Service and the Copernicus Marine Service.
