How many people could die from El Niño worldwide? Which American states could face the greatest heat-related risks?

Climate Impact Lab, a research team that combines experts from the University of California, Berkeley, the Energy Policy Institute at the University of Chicago (EPIC), Rhodium Group, and Rutgers University, has built a tool that tracks how deadly El Niño can be to human life and which parts of the world will be the most impacted.

The tracker provides monthly data on El Niño-related death projections.

Climate Impact Lab co-founder Michael Greenstone says, “Our research puts new forecasting capabilities to work to answer one of the most urgent questions we face: where is extreme heat likely to cost lives?”


Greenstone, who is also the Milton Friedman Distinguished Service Professor in Economics at the University of Chicago, further adds, “Being able to anticipate the deadly effects of extreme heat is a major step forward. It means we can identify where people face the greatest risks and give decision-makers a chance to act before lives are lost. The Tracker provides this information for the Super El Niño we’re living through today.”

The major hotspots

The Global South will likely be most impacted by El Niño - Climate Lab projects 56,000 deaths in the next six months. India will likely see the most El Niño-related deaths in March, with total casualties of about 55,000. Indonesia is likely to lose 29,000 lives to El Niño heat. Brazil is projected to face about 19,000 deaths.

Global projected additional heat deaths between June 2026 and March 2027 are reported as 857,400, whereas deaths projected between October 2026 and March 2027 are 372,900.

The tool projects Southeast Asia as a major hotspot.

The report suggests these El Niño casualties can be minimized by taking appropriate measures like directing emergency response and resilience efforts to the most sensitive regions.

“The data also underscore the importance of addressing extreme heat and its deadly consequences in preparing for El Niño, alongside the extensive work already underway to combat threats to food security,” says Climate Lab’s Faculty Head of Research, Tamma Carleton, an Assistant Professor at the University of California, Berkeley.

Researchers are expecting Super El Niño to raise global temperatures by 1.2°C/2.1°F above normal in the coming months. This could lead to 44% more extremely hot days than we saw in previous years. El Niño is exposing the world to temperatures that were projected to occur 20 years from now due to climate change.

How will the US be impacted?

The United States recorded 145,321 heat-related emergency department visits between January 1 and September 10, 2026, according to data analysed by the Centers for Disease Control and Prevention (CDC).

Of these, approximately 21,775 visits, or 15%, occurred within just 10 days, between June 28 and July 7, across seven regions covering much of the eastern, midwestern and southern United States.

During this period, around 221 million Americans, representing 65% of the country's population, experienced at least one day of major or extreme heat risk.

Researchers found that daily heat-related emergency visit rates were substantially higher than those recorded during the same dates between 2018 and 2025. Men aged 26–54 were particularly affected in most of the regions studied.

Expected impacts during the winter months (December 2026 to February 2027) include a warmer North and a wetter South and East, says the National Oceanic and Atmospheric Administration.

“As we know from decades of observations, a very strong El Niño will likely bring a southward and eastward shift to the jet stream for the contiguous U.S., which tilts the odds toward stormier weather across the South,” said Ken Graham, director of NOAA’s National Weather Service. “While higher chances of rain and snow may bring relief to drought-afflicted areas, too much precipitation on dry soil can fuel destructive flash floods and mudslides. Now is the time for communities and individuals to plan for the upcoming winter.”