How El Niño Works
In 2026 sea temperatures in the eastern equatorial Pacific rose more than 3 °C above average, a record by daily measurements; California declared a state of emergency and Thailand's water agency warned of dry spells lasting into 2027. This film explains the fundamentals: the normal Pacific, with trade winds piling warm water in the west and cold water welling up off Peru; how El Niño begins when those winds weaken and warm water sloshes east; the feedback Jacob Bjerknes described in 1969 and the pressure seesaw Gilbert Walker named in 1923; La Niña, the opposite phase; how NOAA measures an event in the Niño 3.4 region and why it switched to a new index in 2026; the great El Niños of 1982, 1997 and 2015; how one patch of warm ocean shifts rain and drought from Indonesia and Thailand to the Americas and Africa; and why El Niño years tend to set global heat records.
When the Pacific changes its mind
One warm patch of ocean, weather everywhere.
The normal Pacific
Wind, water and a loop of air.
When the winds tire
The warm water sloshes back.
Measuring a giant
One box of ocean, one number.
Around the world
Move the rain, and everything moves.
Heat, and what comes next
An ocean breathes out.
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