With El Niño Storms, California could be in for a very active winter.
As the 2026–27 winter season approaches, one of the biggest factors attracting attention from weather forecasters is a strengthening El Niño Storms developing across the tropical Pacific Ocean.
What Is El Niño?
El Niño is a natural climate pattern involving unusually warm ocean temperatures in the central and eastern tropical Pacific.
Those warmer waters can influence atmospheric circulation far beyond the tropics. During El Niño winters, the jet stream and Pacific storm track can shift in ways that favor more storms reaching California.
Historically, El Niño has been associated with increased precipitation across California, although the effects can vary considerably from one winter to another.[
And that variability is important.
An El Niño storms forecast is not the same thing as a traditional weather forecast. It can tell us that the odds of certain seasonal patterns are increasing, but it cannot tell us exactly when a major atmospheric river will arrive in Los Angeles, San Francisco, Sacramento or other parts of California.
Why Winter 2026–27 Could Be Different
The current El Niño storms event is attracting particular attention because of its projected strength. NOAA reported in August that sea-surface temperatures in the eastern equatorial Pacific had risen to more than 2°C above average in some areas. NOAA also projects a greater than 90% chance of a very strong El Niño during the Northern Hemisphere fall and winter.
A stronger El Niño can increase the odds of the typical El Niño pattern, but it does not guarantee that every expected impact will occur.
For California, one of the biggest potential consequences is an increase in Pacific storm activity and precipitation.
Could California See More Major Storms?
It is possible.
A wetter El Niño winter can bring California more frequent or stronger periods of rain, including storms fueled by moisture from the Pacific.
Some of these systems can develop into atmospheric rivers — long, narrow corridors of concentrated moisture that can transport enormous amounts of water toward the West Coast.
When an atmospheric river makes landfall, it can produce beneficial rainfall and mountain snowfall. However, a particularly strong or slow-moving storm can also bring flooding, mudslides, damaging winds, downed trees and dangerous travel conditions.
The important point is that El Niño raises the seasonal risk; it does not guarantee that every storm will be extreme.
What About Snow in the Sierra Nevada?
More precipitation does not automatically mean more snow.
Whether a particular storm produces heavy Sierra Nevada snowfall depends on temperatures, snow levels and the exact track of the storm.
Some winter storms could bring significant mountain snow, while warmer systems could produce heavy rain at elevations that normally receive snow.
This means California could potentially experience both beneficial mountain snowfall and periods of dangerous rain during the same winter.
For California, that matters because El Niño can shift the Pacific storm track and increase the odds of wetter-than-average conditions across much of the state. But that does not mean California will experience nonstop rain or that forecasters can already identify individual storms months ahead of time.
Northern and Southern California May See Different Impacts
California is a large and geographically diverse state, so an El Niño winter will not necessarily affect every region in the same way.
Southern California often receives particular attention during strong El Niño storms because the storm track can favor increased precipitation across the southern part of the state.
Northern California can also experience major storms and atmospheric rivers, but the relationship between El Niño and precipitation is more complicated than simply saying “El Niño means more rain everywhere.”
Local geography, the position of the jet stream, atmospheric pressure patterns and other climate patterns can all influence where individual storms travel.
Could There Be Flooding?
Yes, and this is one of the major concerns associated with a potentially active California storm season.
After periods of dry weather, the ground may initially absorb substantial rainfall. But repeated storms arriving close together can increase runoff and saturate soils.
Heavy precipitation can create risks including:
- Flash flooding
- River flooding
- Urban flooding
- Mudslides and debris flows
- Road closures
- Falling trees and power outages
- Dangerous mountain travel
- Coastal impacts during strong storms
Areas recently affected by wildfire can face additional debris-flow risks when intense rainfall falls over steep, burned terrain.
Don’t Expect Forecasters to Know the Exact Storms Yet
One of the biggest misconceptions about seasonal weather forecasts is that they can predict individual storms months in advance.
They cannot.
As of August 2026, forecasters have a strong signal that El Niño will influence the upcoming winter, but the details of individual December, January, February and March storms will only become clear as those weather systems develop.
That means headlines claiming that a particular “historic storm” is already guaranteed to hit California should be treated cautiously.
The more reliable message is this: California has an elevated potential for a wetter and more active winter pattern, but the exact number, strength and timing of storms remain unknown.
When Will We Know More?
Forecast confidence will increase as winter approaches.
NOAA’s Climate Prediction Center continually updates its seasonal outlooks and monitors the development of El Niño. Its current seasonal modeling also extends through the 2026–27 winter and spring.
Short-range forecasts become much more useful once individual storm systems are developing over the Pacific. That’s when meteorologists can begin determining whether a particular storm will bring heavy rain, snow, strong winds or atmospheric-river conditions to California.
The Bottom Line
California could be headed toward a notably active winter in 2026–27.
The reason is El Niño, which is currently strengthening in the tropical Pacific. NOAA expects the event to remain strong into the upcoming winter, and historical El Niño patterns favor increased precipitation across California.
But an El Niño winter does not mean California will be hit by one giant storm after another.
Instead, residents should think of El Niño as shifting the odds toward a wetter and potentially stormier winter. Some storms could be beneficial, bringing water to reservoirs and snow to the Sierra Nevada. Others could create serious hazards, particularly if multiple storms arrive in rapid succession.
The safest approach is to watch the forecasts as winter gets closer, prepare for periods of heavy rain and strong winds, and pay particular attention to official National Weather Service warnings when major storms develop.
Winter 2026–27 may be one to watch closely — but the real story will unfold one storm at a time.
