La Niña and its opposite, El Niño
La Niña forms when surface temperatures in the tropical Pacific Ocean are about 0.5°C (0.9°F) below normal for three months. El Niño is the reverse, with temperatures warmer than normal. The chart shows the three-month rolling average temperature anomaly.
A line chart shows 75 years of El Nino and La Nina periods, which seesaw back and forth every few years.
