The answer isn’t quite as simple as forecasters pumping various inputs into computer models that then spit out what we can definitively expect. The Bay Area’s weather patterns are created by global patterns in the atmosphere, everything from interactions with the ocean, landscape and sun.
El Niño — the opposite of La Niña, which recently ended a cycle — generally occurs every three to five years when ocean waters along the equator in the eastern Pacific warm by at least a half-degree Fahrenheit. That, in turn, can reposition the jet stream and funnel storms toward the West Coast of the U.S., often resulting in increased rainfall across thousands of miles.
Climate forecasters predict a range of strengths for the current El Niño — everything from a moderate to a super El Niño — which can often be characterized by intense warmer downpours.
“There is potential for a lot of strong storms with coastal issues, and we just do not have extensive flood systems on the coast of California,” said Gary Lippner, deputy director for flood management and dam safety with the California Department of Water Resources.
With winter just a few months away, climate and weather experts suggest preparing our homes and lives for the worst — major flooding. Keep reading for what to know about 2023’s El Niño, from its impact on California’s snow forecast to the timing of weather predictions.
Is it possible to predict what winter 2023 will be like in California?
Kind of. It’s not possible to predict the day-to-day weather this far in advance. However, meteorologists are able to forecast possible climate changes that might happen.
“Right now, it is still too far out and our seasonal forecasting capabilities are very limited,” said Michael Anderson, California’s state climatologist.
There’s a 30% chance of a “historically strong” El Niño event, which could rival the ferocity of the 1997–98 years, according to NOAA’s latest El Niño Advisory, which saw flooding rains across the state. The scientists note that while a stronger El Niño can increase the likelihood of weather anomalies, it does “not necessarily equate to strong impacts locally.”
That’s because it’s usually only in the worst El Niño years that the entire state gets soaked — Southern California, on the other hand, has a slight tendency toward wetter conditions even in moderate El Niño years. (More on this below.)
Jan Null, a meteorologist with Golden Gate Weather Services, said the relationship between El Niño and Bay Area impacts is not always clear and that the best thing to do as a California resident is to prepare for the worst outcome.
“Climate models are showing this ambivalent pattern for California this winter,” he said.
“The closer we are to that winter rainy season forecast, obviously the better the prediction will be,” said John Chiang, a UC Berkeley climate scientist.
What are the chances of a super El Niño?
While most predictions of the intensity of El Niño range from moderate to strong this year, one forecasting group is predicting what they classify as a super El Niño on par with 1997–98. That winter saw a great deluge across the state, as rivers swelled, mudslides destroyed homes and roads filled with debris. At the end of it, 17 people had died and the state suffered nearly $1 billion in damage.
“It’s only been seen three times previously in the historical record,” said Stephen Yeager, project scientist with the National Center for Atmospheric Research. “We are looking at the potential of a major season-long event that could impact people and their livelihoods.”
For Yeager’s model, he and his team analyzed historical conditions from 1970 to 2019. They took atmospheric conditions into account — warmth, humidity and wind— as well as the state of oceans, ice and land. They then compared that historical data with computer model forecasts, which unveiled the potential for a super El Niño this winter.
“Our system is predicting a warmer event than many other [models],” Yeager said. “But it isn’t out of the realm of possibilities.”
Does a strong El Niño prediction mean a wet winter?
No, not all El Niños are the same. And even a strong system doesn’t mean California will get walloped by atmospheric rivers.
When looking at the historical record, Null said El Niño years have almost equally had above-average and below-average rainfall. For instance, the years of 2015–16 produced a very strong El Niño event but were relatively dry.
“Trying to say this is going to be a strong or very strong event doesn’t equate directly to ‘it’s going to be a wet year in California,’” he said.
He adds that an alphabet soup of other natural phenomena factor into the strength of El Niño and its potential effects, including the Madden-Julian Oscillation, the Pacific Decadal Oscillation and the North Atlantic Oscillation.
Does a wet winter always bring snow to California?
A wet winter does not always mean ample snow. Chiang, with UC Berkeley, said that El Niño tends to have warmer weather patterns, which can actually decrease snow amounts.
“That does play a role — but if you are high enough and cold enough, it will snow rather than rain,” he said.
Chiang adds that the effects of El Niño are not ubiquitous across the world, country or even one state. The climate system can mean wetter weather patterns in California and the Southwest and warmer weather in the Northwest.
At what point in the year do we begin to get firmer predictions for winter?
The only time we can really know what winter will be like is the moment that it ends, said Null, tongue in cheek.
Last year, the seasonal forecast for California’s winter was an even split for a wet or dry winter — and a few months later, torrential rain pounded the state for months.
Around mid-November, Yeager said the forecast will come into better clarity, when updates to weather predictions come out. Around that time, forecasters will outline the potential weather possibilities for the next few months.
But if last winter’s storms taught him anything, said Yeager, predictions can change rapidly, meaning storms could become more intense or back off in severity. Because of the varying predictions — and his super El Niño forecast — he thinks all Californians should prepare for a wet winter.
“If I were living in San Francisco and considering repairing my roof, I might do it based on this information,” he said.
Is climate change intensifying El Niño?
The impact of human-caused climate change on El Niño conditions is hard to pinpoint. Scientists hypothesize it is having an effect, making the impacts from it and La Niña more extreme.
Basically, the wets will become even wetter in California. But the science is still not settled on that, said Yeager.
With ocean temperatures soaring and record warmth this past summer, scientists like Null see a correlation with climate change — but say that it needs to be further proven and studied.
“Every weather event, whether during El Niño or La Niña, has some climate change DNA,” he said.
How should we prepare for a wet year?
First up, understand just how much you — and your home — could be affected by a winter storm of the magnitude we saw earlier this year. Previous storms in the Bay Area have knocked down trees, flooded roads and cut power to tens of thousands of homes and businesses, and contributed to several deaths.
UC Berkeley’s Chiang suggests California property owners should be especially prepared for potential torrential downpours, and consider preemptive measures like fixing leaky roofs, clearing drains and cleaning gutters. Last winter, parts of Chiang’s own Bay Area home flooded and his roof leaked. This year, he prepared by fixing drainage issues around his house and replacing the roof on his home. Read more about preparing your home for potential flooding.
If your home experienced flooding during previous storms this year — or in storms from years past — officials recommend having sandbags, plastic sheeting and other flood control materials ready. Counties, public utilities and even community organizations across the Bay Area will often distribute free sandbags during the rainy season or ahead of a big forecast storm.
Following the atmospheric river storms that hit Northern California over the 2022–2023 winter, officials around the Bay Area doubled down on efforts to keep waterways and storm drains clear to reduce the risk of flooding in residential areas. Both Oakland and San Francisco have programs where residents can “adopt” a storm drain in their community and help remove leaves and other debris.
FEMA also has created a tool that tracks which parts of a city are under flood risk — and to what extent. You can input your address in the FEMA Flood Map Service Center. Once the map tool locates your address, you can select the “Dynamic Map” option to see a more detailed map that may have certain neighborhoods or blocks color coded to represent flood risk.
Carlos Cabrera-Lomelí, Emma Silvers, Carly Severn, Daisy Nguyen and Erin Baldassari contributed flood preparation reporting to this story.
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