Millions of Americans are gearing up for an El Niño threat across the Eastern Pacific with above-average water temperatures. El Niño is one of three phases of a climate cycle called the El Niño-Southern Oscillation (ENSO).

Millions of Americans are gearing up for an El Niño threat across the Eastern Pacific with above-average water temperatures. El Niño is one of three phases of a climate cycle called the El Niño-Southern Oscillation (ENSO).