Super El Niño Could Cause 451,000 Heat Deaths by February 2027, Report Warns

The 2026 Super El Niño is a climate pattern characterized in part by above-average ocean temperatures in a portion of the Pacific Ocean near the equator, and it influences extreme weather across the globe. Meteorologists have warned of its potentially historic consequences since it developed at the start of the summer. The World Meteorological Organization forecast earlier in September 2026 that this El Niño could become the strongest on record, with its most severe impacts still ahead, and predicted the supersized phenomenon will not reach peak intensity until closer to the end of 2026. The U.S.-based Climate Prediction Center expects El Niño will likely remain in place through the Northern Hemisphere winter season, and possibly last into spring.

On September 23, 2026, the University of Chicago's Climate Impact Lab published a report estimating that the current Super El Niño will cause 451,000 additional heat-related deaths between June 2026 and February 2027 compared with an average year. The research hub said 239,000 of those deaths are projected over the next six months, from September 2026 through February 2027. The report finds the heat deaths will be concentrated overwhelmingly in the Global South, on top of impacts from droughts, wildfires and flooding expected as this El Niño could become the strongest on record.

The study combined seasonal temperature forecasts with localized estimates of how high temperatures affect mortality across more than 24,000 regions worldwide, comparing El Niño-driven temperatures with conditions over the last three decades. A 2022 study divided the world into 24,378 regions and estimated a U-shaped relationship between temperature and excess deaths, with more deaths occurring in extreme cold or heat, and the precise shape varying from place to place depending on adaptation and affordability of things such as air conditioning. The researchers combined this approach with the seasonal forecast from the European Centre for Medium-Range Weather Forecasts (ECMWF).

Michael Greenstone, a co-founder of the Climate Impact Lab and the Milton Friedman Distinguished Service Professor in Economics at the University of Chicago, said the projection is made up of ordinary people. "We have long been able to predict the impacts of temperatures on crops, and now we can predict their impact on the worst outcome, death," he said in a statement. "The result is that we now can estimate that 451,000 people may die in the coming months due to El Niño. This is such a large number that it can be numbing, but it is made up of parents and children, grandparents and neighbors, people going to work, caring for families, and living their lives."

Key Facts

The report's global toll is roughly 65 times the 6,800 people believed to be dead or missing from the recent Nepal flash flood. Global land temperatures during this El Niño could be higher by about 1.2 degrees Celsius (2.1 degrees Fahrenheit), producing 44% more extremely hot days than in a typical year. The death projections were compared to the same months of an average year between 1996 and 2025.

Over just the next six months, the report projects 66,800 additional deaths across the Sahel in Africa, with nearly half of those lives lost in Nigeria (31,400). Sudan will face 17,500 additional heat deaths, Niger 10,000, and Chad 8,000. In South East Asia, the extra heat is projected to cause an additional 19,400 deaths in the Philippines, Vietnam, Thailand and Cambodia, and 19,300 deaths in Indonesia. India is projected to see 15,800 more deaths, while Brazil is most impacted in South America with 13,300.

The United States is also in the top 20 affected countries, with a projected 3,500 deaths. The report divides people into three age groups: 4 or under, 65 or above, and the rest; the oldest group is most sensitive, followed by infants. The report identifies Nigeria as where the most El Niño heat deaths are expected.

NBC News reported on September 23 that the heaviest toll is expected in poorer countries, already struggling with food insecurity and high energy costs, partly due to climate change and the fallout of the war in Iran. The report says the Sahel region in Africa is expected to be hardest hit. Other hot spots include about 19,400 additional deaths across the Philippines, Vietnam, Thailand and Cambodia, 19,300 in Indonesia, 15,800 in India and 13,300 in Brazil.

CBS News reported on September 23 that countries across the Global South are forecast to see the greatest impacts, with Nigeria, Sudan, Niger and Chad expected to record more than 65,000 heat-related deaths combined. The Philippines, Vietnam, Thailand, Cambodia and Indonesia are expected to record close to 40,000 deaths collectively, while Brazil and India could also see high death tolls.

Analysis

The bigger picture here is that the projected death toll is not a worst-case scenario but a central estimate derived from observed temperature-mortality relationships. The report has not yet been peer-reviewed, but it uses peer-reviewed methodology. A Climate Impact Lab spokesperson said the findings were released before peer review because there is still time for policymakers to act: "Given that there is still time now for policymakers and others to take action to prevent these deaths, we felt our findings couldn't wait for the peer review process to play out. That would certainly be too late to act for this El Niño cycle."

Independent scientists offered qualified support. New Scientist reported on September 23 that Christopher Callahan at Indiana University Bloomington said, "I do find these results plausible," though he notes the report looks only at heat-related deaths, while El Niño also influences wildfire in Indonesia, infectious disease in South America and flooding in the western US, so the total death toll may be higher. Raquel Nunes of the University of Warwick said the estimate "should not be viewed as a definitive prediction" but highlights the urgent need for preparedness and anticipatory governance.

What this really means is that the 451,000 figure is a planning tool, not a prophecy. The report says the current El Niño is a "postcard from our future," bringing temperatures climate change is projected to deliver 20 years in the future. Tamma Carleton, Faculty Head of Research for the Climate Impact Lab and an Assistant Professor at the University of California, Berkeley, said: "Increasing emergency response and better targeting our efforts can save many lives this year. But 20 years from now, once today's extreme temperatures become the new normal, we don't want to be in a constant state of emergency."

Scripps News reported on September 23 that heat is the most deadly form of extreme weather, although heat deaths are not well-tracked, even in rich nations. The researchers believe this number is likely to rise. El Niño is expected to last until the Northern Hemisphere spring, meaning its heat impacts will linger into the summer months. Emily Grover-Kopec at the Rhodium Group said, "We're hoping this information is actionable, that decisions can be made to move resources ahead of time," and "I fully expect these numbers to get bigger, unfortunately."

Why It Matters

The report stresses that the deaths are preventable with targeted action. Recommended measures include heat-warning systems, cooling centers, hydration stations, protections for outdoor workers, expanded hospital capacity and targeted outreach to the elderly, plus "anticipatory financing" so governments can move resources before dangerous heat peaks. Greenstone said the report "allows decisionmakers to see exactly where emergency actions can be taken now to save tens of thousands of lives in the coming months," and can help humanitarian organizations allocate emergency funds.

The geographic concentration of the toll raises questions about global equity. Greenstone noted that wealthier places generally have greater access to air conditioning, reliable water supplies and functioning health systems. "If you're already in a hot place, the extra couple of degrees are going to be much more dangerous," he said. Abhiyant Tiwari, a heat expert at NRDC India who was not involved in the study, said the projections should serve as a call to action.

The comparison to the Nepal flash flood underscores the scale. The 451,000 deaths projected to occur during the first nine months (June-February) of El Niño are about 65 times larger than the 6,800 people believed to be dead or missing from the recent Nepal flash flood. The report says the toll is on top of the impacts from droughts, wildfires and flooding expected as this El Niño could become the strongest on record.

Next Up

The researchers will update their projections as El Niño progresses. El Niño is expected to persist into the northern hemisphere's spring, so there will be another wave of deaths there after February. "We're going to see anomalously high mortality numbers move north," says Grover-Kopec. The World Meteorological Organization forecast that the supersized phenomenon will not reach peak intensity until closer to the end of 2026.

The Climate Impact Lab said the findings were released before peer review because there is still time for policymakers to act. The report says the current El Niño is a "postcard from our future," and Carleton warned that once today's extreme temperatures become the new normal, "we don't want to be in a constant state of emergency."