El Niño is a climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean. It is the warm phase of the El Niño-Southern Oscillation (ENSO) cycle, which is a cycle of warm and cold sea surface temperature (SST) of the tropical central and eastern Pacific Ocean. During El Niño, trade winds weaken, and warm water is pushed eastward towards South America, causing a shift in atmospheric circulation and weather patterns around the globe. Some key features of El Niño include:
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Warm ocean water: El Niño is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific, including the area off the Pacific coast of South America.
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High air pressure in the western Pacific and low air pressure in the eastern Pacific: This is a characteristic atmospheric circulation pattern during El Niño.
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Increased rainfall: During the development of El Niño, rainfall develops between September–November.
El Niño can have global impacts on weather, wildfires, ecosystems, and economies. Episodes of El Niño typically last nine to 12 months, but can sometimes last for years. El Niño events occur irregularly at two- to seven-year intervals.
