This year’s El Niño is not ‘run-of-the-mill’—and it could rival one that killed 23,000

An intensifying El Nino, nature’s heat-releasing thermostat that spikes global temperatures, is heading to historically strong levels, the U.S. National Oceanic and Atmospheric Administration said Thursday.

In its monthly update, NOAA said this year’s El Nino, a natural warming of the equatorial Pacific that alters weather patterns across the globe, has an 81% chance of becoming “very strong” — the top category available — by fall. It should rank among the most intense El Ninos since the weather agency started tracking them in 1950.

Its biggest impacts — from droughts to downpours to heat waves — are likely to be most felt in the fall and winter, meteorologists said.

This El Nino, which formed only last month, already zipped past the weak stage and is now considered moderate with no indications of slowing its strengthening, the government forecast said. Ocean temperatures in key parts of the Pacific that help indicate the El Nino’s strength are at or near record highs for this time of year, partly because it comes on top of ocean warming from human-caused climate change, meteorologists said.

“It’s pretty extreme,” said Emily Becker, a University of Miami scientist who works with the NOAA El Nino forecast team. “Not unprecedented, but very unusual.”

Becker said it will rival the 1997-1998 El Nino, while other meteorologists predict this one could be even stronger. The World Bank said the El Nino that started in 1997 led to 23,000 deaths in weather disasters, increased poverty rates in some countries and cost governments as much as $45 billion.

“This is not a run-of-the-mill El Nino,” said Daniel Swain, a climate scientist with University of California Agriculture and Natural Resources. Not only is it already breaking records for the time of year, but unlike past super El Ninos, it is on top of considerable background warming from the burning of coal, oil and natural gas. “We might not expect to see the exact same impacts from this event as we have seen in historical ones.”

A very strong El Nino — based on ocean temperatures in parts of the Pacific — does not translate to even more intense extreme weather, but makes those conditions more likely, Becker said.

It increases the chances for most of the southern U.S. to be rainier in the winter, Becker said. It also boosts the likelihood of a warmer winter conditions for the northern United States and Canada.

El Nino usually dampens Atlantic hurricane season. Colorado State University, which pioneered hurricane season forecasts, on Wednesday dramatically reduced its prediction for number of storms “due to increased confidence in a strong or very strong El Nino.” The forecasters predict overall hurricane activity in the Atlantic will be “well below normal.”

Global impacts made more likely include a drier Indonesia and a warmer and wetter eastern Pacific, Becker said.

“El Nino also acts as a ‘thermostat’ for global climate by liberating years’ worth of accumulated heat stored in the subsurface tropical Pacific Ocean and dumping it into the atmosphere, where it eventually dissipates–but not before warming the entire planet in the meantime,” Swain wrote in a blog post.

Many climate scientists are predicting that 2027 — because of pent up heat — will break the 2024 global high temperature record set by the last strong El Nino.

“A strong El Nino would raise the odds of dramatic new climate records over the next 6 to 12 months,” said Zack Labe, a climate scientist at Climate Central. It could give a taste of an even warmer world to come, he said.

This story was originally featured on Fortune.com