"El Niño" is a climate phenomenon that refers to a more-than-normal warming of seawater off the west coast of South America that occurs once every three to seven years. This phenomenon often has a major impact on the weather, with consequences such as drought in North and South America and flooding in Southeast Asia.

The opposite effect, an unusual cooling of seawater in the same area, is called La Niña and also has significant effects on the climate.

Investors often anticipate the occurrence of these phenomena and their impact on commodity prices, as droughts and floods can lead to crop failures, which can drive up the prices of certain products and other commodities.