The disruptions of tropical Pacific sea surface temperature and rainfall that occur during the climate pattern called "ENSO" trigger a cascade of global side effects. These maps show how El Niño and La Niña affect seasonal climate around the world.
A strong El Niño continued during December 2015 with well above average sea surface temperatures across the central and eastern equatorial Pacific Ocean, according to NOAA Climate Prediction Center’s monthly El Niño advisory update.
Through June, the eastern Pacific was warmer than average, but the lack of a strong gradient in sea surface temperature anomalies between the eastern and western Pacific may have kept the atmosphere from getting in sync with the developing El Niño.
A pool of warm water lurking beneath the surface of the western Pacific has been slowly sloshing eastward in the past few months. This traveling wave of warm water is one of the signs that climate conditions are favorable for the emergence of El Niño later this year.