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Changing weather conditions in Tropical Pacific as El Niño emerges
This is animation showing the changing conditions in Tropical Pacific this year, La Niña fading and El Niño emerging.
OAKLAND, Calif. - Some of this year's forecast models, including those from the Climate Prediction Center, have suggested that the pending El Niño event for the winter of 2026-2027 could approach the higher extreme of the very strong range. If this were to happen, it could be a record-setting event and may drastically affect the winter storm patterns.
What is El Niño?
El Niño is a recurring natural climate pattern that has its origins in the Pacific Ocean. While there are always changing patterns in the offshore waters adjacent to the Bay Area, the region that forecasters examine is over 3,000 miles away in the Equatorial Pacific.
El Niño winter pattern
The developments in the El Niño region can affect the winter storm track. While there are no guarantees, El Niño conditions can boost the potential for above average rainfall in parts of California.
A strong El Niño has the potential to shift the winter storm track, boosting the odds for an active winter for parts of the United States. In California, there is a higher chance of above normal rainfall for the southern half of the state.
La Niña shift to El Niño
This graphic shows the rapid changes in the Equatorial Pacific (El Niño Region). Back in January of 2026 there were La Niña conditions (water temperatures cooler than average). El Niño conditions developed over the summer (brighter colors). El Niñ …
This animation shows the changing conditions in Tropical Pacific this year, with La Niña fading and El Niño emerging.
Very Strong El Niño in 2015-2016
While there were high expectations for above average rainfall during the last El Niño event in 2015-2016, parts of the Bay Area recorded below average rainfall.
El Niño region
The El Niño region is not adjacent to the Bay Area coast. The region of interest is over 3000 miles away in an area called Niño 3.4. This is where water temperatures are monitored by satellite and buoys.
This region is called Enso 3.4. This is the defined area where researchers monitor sea surface temperatures. If warmer than normal water temperatures are observed, El Niño conditions are present.
El Niño intensity scale
There is an intensity scale for El Niños: Weak, Moderate, Strong, Very Strong. What are the requirements for a Very Strong El Niño? The water temperatures in the Equatorial Pacific, over a 3 month period, must exceed 2 degrees Celsius.
The magnitude of the warming dictates the strength of El Niño.
The intensity scale runs from weak to moderate to strong to very strong.
Previous Very Strong El Niños in the Bay Area
There have been 4 Very Strong El Niños on record: 1982-1983, 1991-1992, 1997-1998, 2015-2016. Precipitation for the San Francisco Bay Area was well above of the average in two of the events. The last event in the winter of 2015-2016 yielded average …