El Niño and La Niña are the two opposite states of a natural climate phenomenon called the El Niño Southern Oscillation (ENSO).
El Niño and La Niña occur in the Pacific but can affect weather systems across the world.
The two states are often identified by sea surface temperatures in the tropical eastern and central Pacific Ocean. During El Niño, these waters are warmer; during La Niña, they are cooler.
