This year's El Niño is on track to be the strongest on record, threatening to unleash extreme weather across the globe and make 2027 the hottest recorded year by far. It is expected to be the most "intense" El Niño in more than a century, the head of long-range forecasting at the U.K.'s Met Office warned Friday.

Stacked on top of long-term human-caused climate change, the temporary jolt will offer a glimpse of the heat the world can expect by the late 2030s, experts say.

Here's what to know.