Federal forecasters announced on June 13, 2026, that El Niño conditions have officially developed in the tropical Pacific Ocean, with expectations that the climate pattern will strengthen into a moderate or strong event by fall and peak during the 2026-2027 winter. The National Oceanic and Atmospheric Administration’s National Weather Service issued an El Niño Advisory, confirming that sea surface temperatures in the equatorial Pacific have risen at least 0.5°C above average for several consecutive months.
Forecasters now estimate a 63% chance that temperatures in the key Niño-monitored region will exceed 2.0°C, a threshold that would classify the event as “very strong.”
El Niño, Spanish for “little boy,” is the warm phase of the El Niño Southern Oscillation (ENSO). It occurs when the Walker Circulation—a massive east-to-west air flow driven by temperature and pressure differences between the warm western Pacific and cooler eastern Pacific—breaks down, allowing warmer water to shift eastward toward South America.
NOAA monitors both ocean temperatures and atmospheric patterns to declare an El Niño event.
For residents of Modoc County and the town of Likely, the development of El Niño carries specific implications for the upcoming winter. During a typical El Niño winter, the jet stream over the North Pacific shifts southward, bringing storm tracks across the southern tier of the United States.
This often results in drier conditions for the Northern Rockies and the Ohio and Tennessee valleys, while the northern U.S. tends to experience warmer-than-usual temperatures.
However, NOAA officials caution that each El Niño is unique. “Every El Niño is not the same; each one is unique with its own imprint on our weather,” said Ken Graham, director of NOAA’s National Weather Service.
“Advanced monitoring and an improved understanding of El Niño patterns allow the NWS to better predict and better prepare the public and our core partners for what is to come.”
Beyond temperature and precipitation changes, El Niño can influence hurricane activity. Stronger upper-level winds over the Atlantic Basin tend to suppress storm and hurricane development, while weaker winds in the eastern and central Pacific can enhance tropical cyclone formation.
The pattern also increases the risk of high tide flooding along the U.S. West Coast and can alter the migration of fish and other marine organisms, with warm-water species moving north and cold-water species retreating farther north or into deeper waters.
Past El Niño events have also been linked to an increase in harmful algal blooms along the West Coast.
In February 2026, NOAA adopted a new monitoring index called the Relative Oceanic Niño Index (RONI), which updates monthly to reflect evolving ocean temperatures. This replaces the traditional Oceanic Niño Index (ONI), which relied on a static 30-year baseline.
Officials say RONI provides a more reliable method for identifying El Niño and La Niña events in a changing climate.