The El Niño climate pattern has officially begun and is forecast by the National Oceanic and Atmospheric Administration to strengthen into a very strong, or “Super,” El Niño, with a 63% chance of reaching that level. NOAA’s Climate Prediction Center says the event could become one of the largest in the historical record dating back to 1950, and it is giving 100% odds that El Niño will continue through the fall with very high odds that it lasts into winter.
El Niño develops when unusually warm water builds in the central and eastern tropical Pacific Ocean, changing wind patterns and sending ripple effects through weather systems around the world. In this case, large amounts of heat have been moving eastward below the ocean surface for months and are now beginning to rise closer to the surface near South America, a process similar to what has occurred during past strong El Niño events.
A Super El Niño is generally defined by tropical Pacific waters running more than 2 degrees above average. Several computer models suggest this threshold could be exceeded by a wide margin. Such events are relatively rare, with the most recent major El Niños occurring in 2015-16, 1997-98 and 1982-83.
Forecasters say the event is likely to add to the planet’s already rising temperatures caused by human-driven climate change. Because El Niño transfers heat from the ocean into the atmosphere, it can temporarily lift global average surface temperatures even higher. NOAA-linked projections suggest this could virtually guarantee that 2027 will surpass 2024 as the warmest year on record.
The weather impacts of El Niño vary by region but often include stronger heat waves, flooding, drought and changing storm tracks. In the United States, the effects are usually most noticeable during winter. Warmer-than-average conditions are often seen across the northern U.S., western Canada and Alaska, while the southern U.S. tends to be wetter and cooler due to a more active jet stream. California could also face more frequent atmospheric river events, though the exact locations most affected remain uncertain.
El Niño can also influence hurricane activity. It often increases hurricane formation in the central and eastern Pacific while suppressing Atlantic hurricanes. That pattern could raise risks for the Southwest United States and Hawaii depending on storm paths.
Across the globe, El Niño is associated with drought and heat in places such as Australia, Indonesia and parts of the Caribbean, as well as reduced monsoon rainfall in India and Southeast Asia. It can also contribute to flooding in parts of Africa and South America, while increasing the chance of heavy rain in areas such as Peru and sections of southeastern South America.
Ocean ecosystems may also suffer. El Niño often triggers marine heat waves and coral bleaching because corals are highly sensitive to warmer water. Researchers also warn that strong El Niño events can hurt economies by damaging infrastructure, disrupting food supplies and slowing growth.
Even so, scientists caution that every El Niño behaves differently. This one may be especially difficult to predict because it is unfolding in a world that is already much warmer than in past events.
