From Fox news:
Every few years, unusually warm water builds across the equatorial Pacific, weakening the trade winds and shifting tropical rainfall eastward.
The 2015-16 El Niño was also very strong, as elevated sea levels in October 2015 (middle) show. But its pattern differed from those in October 1997 (top) and October 2026 (bottom): less of the elevated water reached the coast of South America, which contributed to different weather patterns that year.
That ocean-atmosphere change can help nudge the jet stream, bringing wetter conditions to the southern U.S. and warmer, drier weather to parts of the northern U.S. and Canada during winter.
Each El Niño develops differently, varying in strength, duration and impacts.
COULD HISTORY REPEAT ITSELF? HOW PAST SUPER EL NIÑO WINTERS OFFER CLUES ABOUT WHAT’S AHEAD
This year, a powerful El Niño is building across the Pacific, with long-range forecasts suggesting the 2026–27 event could rank among the strongest in recent history.