The term El Niño refers to the large-scale ocean-atmosphere climate interaction linked to a. El Niño is the warm phase of the El Niño–Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and. El Niño is the warm phase of the El Niño–Southern Oscillation and 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. El Niño is a climate cycle in the Pacific Ocean with a global impact on weather patterns. During an El Niño event, the surface waters in the central and eastern Pacific Ocean become significantly warmer than usual. El Niño is a climate pattern that describes the unusual warming of surface waters in the eastern tropical Pacific Ocean.