El Niño is a local warming of surface waters that takes place in the entire equatorial zone of the central and eastern Pacific Ocean of the Peruvian coast and which affects the atmospheric circulation worldwide. La Niña refers to the cold equivalent of El Niño. El Niño and La Niña are opposite phases of a natural climate pattern across the tropical Pacific Ocean that swings back and forth every 3 to 7 years on average. El Niño and La Niña can make extreme weather events more likely in certain regions. Predicting the life cycle and strength of El Niño and La Niña is critical for helping people plan for, avoid, or mitigate potential damages in every sector of society, including agriculture, fisheries, energy, water, transportation, and healthcare.