El Niño is the warming phase of the El Niño–Southern Oscillation (ENSO), a climate pattern that arises from variations in winds and sea-surface temperatures over the tropical Pacific. ENSO can affect climate across much of the tropics and subtropics.

El Niño events vary in strength and are difficult to predict. They typically last about a year and occur every two to seven years, with neutral periods in between.

In the Amazon, El Niño can worsen heat and drought, increasing conditions that favor fires. However, the news report notes that most fire ignitions in the region are caused by human activity; dry conditions can allow fires to spread.