an unusual ocean current that happens along the western coast of South America every two to ten years, killing large numbers of sea creatures and causing noticeable and often severe changes in weather conditions in many areas of the world

the El Niño weather pattern/system/phenomenon 厄尔尼诺天气现象

Rains came late to the region because of El Niño. 因为厄尔尼诺现象的影响，这个地区的雨季推迟了。