El Ni ‧ ño /el ˈniːnjəʊ/ BrE AmE
a change in the weather that happens every three to seven years, caused by a rise in the temperature of a large area of the Pacific Ocean off the west coast of South America. El Niño has severe effects on the weather in many parts of the world, and can cause ↑ drought (=complete lack of rain) in some places and heavy rain and violent storms in other places.