Why the World Is Bracing for a Rare ‘Super’ El Niño: Explainer

A cyclical weather phenomenon that can drive flooding in one continent and drought in another looks increasingly likely to emerge this year.

El Niño occurs when the atmosphere reacts to a sustained warming of Pacific Ocean surface temperatures above normal levels. The water has been rapidly heating up in recent months, and the odds of El Niño forming by the end of July have climbed to 82%, according to the US Climate Prediction Center.

The looming El Niño could be particularly powerful. There’s a 67% chance it may evolve into a strong or very strong event — what’s informally known ...