The Climate Impact Lab projects 451,000 additional heat-related deaths worldwide from June 2026 through February 2027. The vast majority of those deaths are projected to occur across the Global South, in regions where air conditioning is rare, early warning systems are limited, and outdoor labor is unavoidable. Nigeria alone is projected to account for 31,400 of the 66,800 deaths forecast across the Sahel. Sudan, Indonesia, India, and Brazil follow with some of the largest individual country tolls.
The projection rests on a climate event that has already broken records before reaching its peak. In the Niño 3.4 region, a stretch of the central equatorial Pacific used as the benchmark for measuring El Niño intensity, the average ocean temperature reached 3.05°C (5.49°F) above normal, the highest sea surface temperature anomaly on record. El Niño reached this level about two months earlier than the previous record holder, the 2015 event. With ocean temperatures still rising, the current event is on track to exceed previous records.
El Niño reshapes rainfall patterns, drives heat domes, fuels wildfires, and intensifies droughts across multiple continents simultaneously. Maps showing the expected effects help illustrate just how differently the same climate pattern can play out around the world. Some regions tend to become wetter during El Niño, while others experience reduced rainfall and greater drought risk.
But another map shows something more directly connected to human health: where researchers project the greatest number of additional heat-related deaths will occur.
The Climate Impact Lab’s analysis focused specifically on excess deaths from extreme heat, and researchers say the projected death toll could continue rising as the event develops.
The Scale of the Projection: What 451,000 Deaths Means
A Climate Impact Lab report finds this year’s “Super El Niño” is projected to lead to 451,000 deaths from extreme hot days, on top of the impacts from droughts, wildfires, and flooding expected from hotter temperatures and shifting rainfall patterns. The 451,000 total covers the first nine months of El Niño, beginning in June.
All of these figures are modeled projections, not counts of recorded deaths, and the analysis has not yet been peer-reviewed. The team applied mortality-temperature relationships developed in peer-reviewed work across 24,378 regions, roughly comparable in population to American counties, then combined them with seasonal temperature forecasts for the El Niño period and average heat mortality from 1996 to 2025. The Climate Impact Lab says the full details of the seasonal mortality projection will appear in a forthcoming peer-reviewed journal publication.
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 projected global toll “is such a large number that it can be numbing,” but emphasized that the figure represents real people and families. Greenstone said the analysis could help decision-makers identify where emergency actions have the potential to save lives.
According to the Climate Impact Lab’s analysis, this El Niño will produce 44% more extremely hot days than would be expected in a normal year. Global land temperatures during this El Niño are projected to be about 1.2°C (2.1°F) above normal, according to NBC News coverage of the study.
The Record-Breaking El Niño Driving the Crisis
El Niño, a natural climate pattern that typically raises global temperatures, has crossed into super-sized territory and is on track to become the strongest ever recorded. Water temperatures in the central equatorial Pacific have been at record levels for more than three months straight, with cascading effects on global climate expected to peak late this year and into next.
NOAA’s Climate Prediction Center has indicated El Niño is strengthening, with a greater than 90% chance of a very strong event during the Northern Hemisphere fall and winter of 2026 to 2027, and a 75% chance that the event will exceed the strength of every El Niño in its record since 1950 during October through December. The UK Met Office has warned that this El Niño is likely to be “the largest since the 19th century.”
Ocean temperatures in the central Pacific are projected to reach an average peak of around 4.1°C (7.4°F) above average in December, about a degree higher than the record-breaking El Niño in 2015. The World Meteorological Organization has declared, with what it describes as an “exceptionally high likelihood of nearly 100%,” that El Niño will persist through February 2027.
The temporary effects from this very strong El Niño event will amplify long-term warming from climate change, greatly elevating the likelihood of record-breaking global temperatures and extreme weather events during 2026 to 2027. Combined with existing global warming from fossil fuel emissions, the heat consequences are projected to be severe, according to the Climate Impact Lab analysis.
One El Niño, Very Different Effects Around the World
A map featured in coverage of the developing El Niño illustrates why its effects can be so difficult to summarize.
The map, based on information from the International Research Institute for Climate and Society, shows typical precipitation patterns associated with El Niño. Some regions have historically tended toward wetter-than-normal conditions during an El Niño, while others are more likely to experience below-normal rainfall.
That matters because El Niño doesn’t simply make the entire planet hotter or drier in the same way. Changes in Pacific Ocean temperatures alter atmospheric circulation, which can shift rainfall and temperature patterns thousands of miles away.
The precipitation map shouldn’t be interpreted as a precise forecast of where deaths will occur. Instead, it helps visualize how one climate phenomenon can contribute to very different hazards in different parts of the world, including drought, flooding, wildfire conditions, and extreme heat.
The Map Shows Where the Greatest Heat Risk Is Concentrated
The projected death toll is also far from evenly distributed.
The Climate Impact Lab modeled heat mortality across 24,378 regions worldwide, allowing researchers to estimate where additional deaths associated with El Niño-driven extreme heat are likely to be concentrated. The resulting geographic analysis highlights particularly severe impacts across parts of Africa, South and Southeast Asia, and other areas of the Global South.
Rather than simply producing a global number, mapping the risk can help identify the provinces and population centers where interventions could potentially save the most lives.
Sub-Saharan Africa and the Sahel
The Sahel region in Africa is expected to be the hardest hit, with about 66,800 additional deaths caused by El Niño-driven heat, according to NBC News coverage of the Climate Impact Lab’s findings. Nearly half of those deaths are projected to occur in Nigeria alone, at 31,400. Sudan is projected to face 17,500 additional heat deaths, according to the University of Chicago’s Climate Impact Lab.
A large share of the working population in these countries labors outdoors in agriculture and informal sectors. Shade, hydration access, and emergency healthcare infrastructure are not uniformly available. When ambient temperatures climb above an already extreme baseline, the physiological margin for survival narrows sharply, particularly for the elderly, young children, and people with underlying health conditions.
Southeast Asia and South Asia
In Southeast Asia, the extra heat is projected to cause an additional 19,400 deaths across the Philippines, Vietnam, Thailand, and Cambodia, and 19,300 deaths in Indonesia, according to the University of Chicago’s Climate Impact Lab. India is projected to see 15,800 additional deaths. In South America, Brazil is the most impacted country, with 13,300 projected deaths from El Niño’s heat.
By modeling at a sub-national level, the Climate Impact Lab can identify which specific provinces and population clusters could be prioritized for emergency response.
The United States
In the US, projected heat-related deaths are smaller in scale relative to the Global South but are not insignificant. The risk is highest in September, as record-hot summer temperatures linger into an unseasonably warm start to fall.
Extreme heat is among the deadliest weather hazards in the United States, causing thousands of deaths each year.
A Glimpse 20 Years Into the Future
The temperatures produced by this El Niño resemble what climate projections suggest will be routine within two decades, according to the Climate Impact Lab report. The event functions as a preview of conditions that climate change is projected to make common some 20 years from now.
Tamma Carleton, Faculty Head of Research for the Climate Impact Lab and an Assistant Professor at UC Berkeley, said increasing emergency response and better targeting of resources could save lives during the current event. Longer term, however, she argued that adaptation needs to move beyond constant emergency response toward infrastructure and planning designed for temperatures that may eventually become commonplace.
Climate change is increasing the frequency of extreme El Niño events, leading to intensifying droughts, worsening floods, and more extreme heat, according to Yale Environment 360. Every public health failure and success during this event generates evidence about what works when temperatures exceed historical norms by a degree or more.
What Can Reduce the Death Toll
The Climate Impact Lab is explicit that the projected death toll is not fixed.
Heat-health early warning systems can be a cost-effective adaptation option that reduces heat-related mortality and morbidity, according to a 2024 review in a peer-reviewed public health journal. These systems work by combining meteorological forecasts with coordinated emergency responses, alerting hospitals, mobilizing social workers, opening cooling centers, and issuing targeted public communications before a heat event peaks.
There is indirect evidence that heat-health warning systems which couple early warnings with emergency response reduce mortality, according to NSF-supported research. Many of the countries facing the largest projected death tolls have limited meteorological infrastructure and public health budgets stretched by existing crises. A warning system that activates 48 hours before a deadly heat event can meaningfully change outcomes; one activated after peak temperatures have arrived cannot.
Cooling centers, designated air-conditioned buildings made available during extreme heat, are a recognized public health strategy, according to the CDC. In rural West African or Southeast Asian contexts, access to electricity and functioning air conditioning cannot be assumed, making the required adaptation infrastructure more complex and longer to deploy than a single hot season allows.
The Climate Impact Lab’s Adaptation Inventory identifies additional protective measures drawn from peer-reviewed research, including shading structures, adjusted work schedules for outdoor laborers, and targeted outreach to elderly populations who face the highest mortality risk from heat exposure. The Climate Impact Lab has indicated it will update its mortality projections as El Niño continues to develop.
Key Takeaways
Nigeria, Sudan, Indonesia, and India face some of the largest projected tolls because their populations include large shares of outdoor workers, elderly people without access to cooling, and communities where baseline temperatures are already extremely high.
Government forecasters put the probability of this El Niño becoming a “very strong” event this fall and winter at above 90%, with a 75% chance of exceeding the strength of every El Niño since 1950. Anomalously warm temperatures are expected to continue through mid-2027, meaning the estimate of heat-related excess deaths could continue to change as the event develops.
Emergency response efforts, including early warning systems, cooling center activation, and outdoor labor protections, deployed now could reduce the mortality burden still ahead. The question is whether resources reach the highest-risk communities before temperatures peak.
The maps help put that challenge into perspective. El Niño is a global phenomenon, but its consequences are profoundly local. The same event can bring excess rainfall to one region, drought to another, and potentially deadly heat to communities thousands of miles apart.
The temperatures this El Niño is generating are projected to become routine within 20 years, according to the Climate Impact Lab. The adaptation infrastructure built or neglected during this event will help determine how many of those future deaths are preventable.
AI Disclaimer: This article was created with the assistance of AI tools and reviewed by a human editor.
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