EL NIÑO / FIELD GUIDE
What Is El Niño?
El Niño is the warm phase of the El Niño–Southern Oscillation (ENSO): warmer-than-average surface waters in the central and eastern tropical Pacific interact with changes in atmospheric circulation.
An ocean–atmosphere pattern
ENSO involves both the ocean and the atmosphere. Warm water alone does not establish an El Niño event. Scientists also examine trade winds, air pressure and tropical rainfall.
One cycle, three phases
ENSO has three phases: El Niño, La Niña and neutral. They describe ocean and atmospheric conditions relative to typical climate, rather than the weather on an individual day.
El Niño and global warming
ENSO is natural climate variability; global warming is a long-term trend. Both can influence temperatures, so El Niño does not explain every hot day or unusually warm year.
References
This article explains established climate science using official sources. Consult the references for background, and always check the publication date of any forecast.
NOAA Climate.gov: background referenceNOAA CPC: ENSO Diagnostic Discussion