Meteorologists predict that La Niña may bring extreme weather to California this year, affecting Northern California and Southern California in significantly different ways.
Because California spans hundreds of miles, these weather extremes can have significant outcomes. Powerful, concentrated storms increase flood risks in the north, and warmer, drier conditions increase wildfire risks in the south. According to the National Oceanic and Atmospheric Administration (NOAA), these effects could last for months, as La Niña events typically last from nine to 12 months.
“Experts and scientists have warned that California will likely experience many years moving forward with warm and extreme dry conditions, with a handful of powerful storms,” said Jason Ince, an information officer for the Department of California Water Resources (DWR).
What is La Niña?
La Niña is the opposite of its cousin, El Niño. Both influence weather patterns around the world, especially in California, and are often mistaken for storm systems.
“They’re climate patterns and not storms that cool the surface waters, typically in the Pacific Ocean,” said Vianey Arana, a meteorologist for National Broadcasting Company (NBC).
These climate patterns affect their regions inversely. According to the National Weather Service, El Niño creates warmer temperatures on the ocean’s surface, shifting the jet streams south, resulting in wetter and sometimes colder conditions throughout the south. La Niña, in contrast, cools the ocean’s surface and shifts the jet streams north, resulting in a drier south and a cooler north with stronger trade winds.
“With that cooling, you get the global wind and weather patterns, specifically here for California, often meaning drier, sometimes cooler winters — the weather extremes that go with it,” Arana said.
Northern California
Due to its unique placement, Northern California may receive a combination of wet and dry periods as a result of La Niña’s effect on jet streams.
“Where La Niña is concerned, we’ve seen boom-and-bust cycles, meaning high-impact floods and drought years, which can be extremes in and of themselves,” said Rob Mayeda, meteorologist for NBC.
However, intense rainstorms will periodically drive the precipitation received close to the annual average. Of the past 22 recorded La Niña years, Northern California received 102% of the annual average precipitation, with Sacramento receiving 96% and the Bay Area receiving 91%, according to the Times Herald.
The effects of climate change could intensify these storms.
“Much of the Pacific Ocean west of California is much warmer than average. Warmer air can hold more moisture, which could mean early-season atmospheric river storms have a higher impact with more rain and wind until ocean conditions shift back closer to near-average temperatures,” Mayeda said.
If these intensified rainstorms, or atmospheric rivers, stay over the same area for an extended period, the precipitation could raise river and stream levels. This elevated flow could trigger flooding near bodies of water affected by the increased precipitation.
“We could have one good storm come in and give the amount of rainfall worth several months in several days. Whenever we’re dealing with atmospheric rivers, there’s a lot of variability that goes into it,” Arana said.
Additional potential damages can come along with flooding and heavy rains. Heavy rains can destroy roads and power lines. Jesse Fripp is the founder and CEO of Shining Rock Ventures, and he and his home in western North Carolina were affected by the heavy rainfall brought by Hurricane Helene in 2024, which caused about $53 billion in property damage according to National Public Radio (NPR). The heavy rains and winds experienced by Fripp and others during Hurricane Helene may be present, to a lesser extent, in amplified river storms brought by La Niña.
“An incredible amount of water damaged our road. But the power went out immediately, and we didn’t quite realize what had happened. The first inkling we had on Friday, we noticed that the cellular services were out,” Fripp said.
If heavy rains, brought on by La Niña, disrupt roads and cell service, transportation and logistics may become challenging or difficult. The loss of powerlines could also result in blackouts, food spoilage, and possible economic loss, as has been seen with previous power outages such as the PG&E shut-off in 2019, according to the Stanford Woods Institute for the Environment.
Southern California
As the jet stream pushes north, rainfall and the cooler temperatures accompanying it are moved away from America’s southern regions.
“For Southern California, the prospect of seeing below-average precipitation would be a problem, not just for persistent fire danger, but this follows one of the driest winters on record, potentially enhancing drought risk and severity,” Mayeda said.
Early-season rainfall may alleviate some of the wildfire threat, providing short-term relief, according to Arana.
Despite this early-season relief, she reminds us that one wind event could change things and bring back wildfire risk into the area, emphasizing the importance of awareness and preparedness.
Populations at risk
Extreme weather poses a threat to several populations. The threats to these populations lie within location and physical ability. Beyond property damage, extreme weather also endangers human health.
“Those at risk, as far as studies and research have shown, are the elderly, kids, and pregnant women. This is based on research from medical professionals and the connection between extreme weather,” Arana said.
According to the National Library of Medicine, for expectant mothers, these risks stem from an increased susceptibility to higher temperatures due to their compromised thermoregulation and homeostasis abilities.
The risk for children comes from their lower body weight compared to adults, as their bodies are still growing and developing, according to the United States Environmental Protection Agency. Behavioral differences also contribute to increased risk for children during extreme weather events.
Older adults often face a weakened immune system and a compromised ability to adapt to hot and cold weather, per the Association of American Medical Colleges (AAMC). Combined with the extreme weather swings projected to occur, this can result in sudden changes from hot and dry temperatures to heavy rainfall. Over 80% of the heat-related deaths in America are in people over 60, according to Harvard Medicine Magazine.
However, other factors besides physical dispositions contribute to the risk of the effects of extreme weather.
“You have to base your risk factor on where you live, such as if you live in an area that is near a creek, near a coastal community, or in an area that has dealt with previous wildfires,” Arana said.
Homes near bodies of water are at greater risk of experiencing flooding when exposed to prolonged periods of rain, as was the case with Fripp, whose property was located near the French Broad River near Asheville, North Carolina. The water level of these bodies rises when exposed to heavy rains, potentially culminating in flooding. Burn scars cannot absorb water due to the lack of vegetation, leading to potential flooding, according to the National Weather Service.
“People most affected tend to be at-risk populations, particularly the homeless. Homeless encampments are often located in flood-prone spaces, which is particularly dangerous when stronger atmospheric rivers hit the Bay Area,” said Paul Heggen, chief meteorologist for Columbia Broadcasting System (CBS).
Protection
If extreme weather does occur, there are many actions one can take to stay safe. The first step is self-assessing the threat level.
“If you live near a creek, and you’re thinking, ‘Okay, I either have been living or just moved here — is my home at risk for flooding? Is that going to be something that impacts you?’ Assessing where you live and where you work will always be something to monitor and look out for,” Arana said.
By completing a self-diagnosis and assessing the danger one is in, one can evaluate the immediacy and potency of the threat. Then, one can create an appropriate plan for preparing and mitigating the impacts of extreme weather.
“The best protection is simple: pay attention to the weather! As much as forecasting has improved over the last few decades, things can change rapidly when a major-impact event is headed toward the coast,” Heggen said.
Paying attention to the news keeps one informed and knowledgeable about current situations. By being informed about potential dangers, one can be prepared for a dangerous situation. If an emergency occurs, prepare to mitigate its impacts by having a clear and well-communicated plan.
“Always have an emergency evacuation kit ready; be prepared to evacuate early; have a plan for where you will go in an emergency and what to do with your pets,” Ince said.
In an emergency, being prepared and having a clear plan can eliminate confusion. By stockpiling medical supplies, food, water, and other essential items, one can also prepare for longer-term survival.
Ultimately, the DWR urges Californians to prepare for potential dangers.
“Because of these extremes, Californians everywhere should think more about their risk from climate disasters of all kinds, including flooding and wildfire. DWR encourages Californians to remember three things to prepare themselves for flood risk: Be Aware, Be Prepared, and Take Action,” Ince said.
