A powerful El Niño event could lead to an estimated 451,000 additional heat-related deaths worldwide between June 2026 and February 2027, according to a new Climate Impact Lab analysis. Researchers warn that the extreme heat could hit countries across the Global South particularly hard, with India, Nigeria, Indonesia, Sudan and Brazil among the areas facing major risks.
A rapidly strengthening El Niño weather pattern could bring an alarming rise in extreme heat around the world, with a new analysis projecting that more than 451,000 additional people could die from heat-related causes by February 2027.
The estimate comes from the Climate Impact Lab, a research group involving scientists, economists and data experts at the University of Chicago and other institutions.
The researchers say the figure represents additional deaths compared with what would normally be expected during the same period. It does not mean that 451,000 people have already died, nor that every projected death will necessarily occur.
The report covers the period from June 2026, when the current El Niño began, through February 2027. Researchers also warn that the eventual toll could rise further because the unusually hot conditions may continue beyond February.
What Is El Niño and Why Does It Matter?
El Niño is a naturally occurring climate pattern linked to unusually warm ocean temperatures in the central and eastern tropical Pacific.
Although it begins in the Pacific, its influence can extend across much of the world. It can change normal patterns of:
- Temperature
- Rainfall
- Drought
- Flooding
- Storm activity
- Wildfires
- Agricultural conditions
A strong El Niño can also push global temperatures higher because it releases additional heat from the tropical Pacific into the atmosphere.
The World Meteorological Organization (WMO) said in September that El Niño was firmly established and expected to strengthen further. WMO forecasts gave an exceptionally high, nearly 100% likelihood that the event would persist through February 2027.
Global Warming Could Make the Heat Even Worse
The concern is not El Niño alone.
Researchers say the current event is developing on top of a world that is already significantly warmer because of human-caused climate change.
According to the Climate Impact Lab analysis, global land temperatures could be around 1.2°C (2.1°F) above normal during the coming months.
The researchers estimate that this could produce approximately 44% more extremely hot days than would normally be expected.
That combination is particularly concerning because extreme heat can become dangerous when temperatures remain high for long periods, especially for people who have limited access to cooling, healthcare and safe working conditions.
More Than 451,000 Additional Heat Deaths Projected
The headline figure from the Climate Impact Lab analysis is stark.
Researchers estimate:
- 451,000 additional heat-related deaths between June 2026 and February 2027.
- Around 239,000 additional deaths are projected for the September 2026 to February 2027 period.
- The estimate is measured against deaths expected during comparable months in an average year.
- The projected deaths are separate from additional losses that could result from floods, droughts and wildfires linked to the changing weather patterns.
- The overall number could increase if unusually hot conditions continue later into 2027.
The researchers describe the current conditions as a glimpse of a warmer future.
Their analysis suggests that temperatures experienced during this El Niño could resemble conditions that climate change models indicate may become much more common within roughly two decades.
Which Countries Could Be Hit Hardest?
The projected impact is not expected to be evenly distributed around the world.
Countries in parts of Africa, South Asia and Southeast Asia are expected to experience some of the largest increases in heat-related deaths.
The Climate Impact Lab estimates that Nigeria could record around 31,400 additional heat-related deaths, making it one of the countries facing the largest projected toll.
Other countries identified as particularly vulnerable include:
- Indonesia
- Sudan
- India
- Brazil
- Other countries across the African Sahel
- Several nations in Southeast Asia
The wider Sahel region is projected to experience approximately 66,800 additional heat-related deaths during September 2026 to February 2027. India is projected to see around 15,800 additional deaths, while Brazil is estimated at approximately 13,300.
India Among Countries Facing Significant Risk
India is one of the countries highlighted in the report because of its large population, existing exposure to extreme heat and regional differences in access to cooling and healthcare.
The Climate Impact Lab projects around 15,800 additional heat-related deaths in India across the June 2026 to February 2027 period.
A substantial share of the projected Indian toll could occur during the cooler months of December through February if unusually warm conditions continue, according to analysis of the report.
For India, the risk is particularly important because extreme heat can affect both urban and rural populations.
People who work outdoors, older adults, young children and individuals without reliable access to cooling can face greater exposure during periods of unusually high temperatures.
The United States Could Also See Additional Heat Deaths
The effects are not limited to developing countries.
The Climate Impact Lab also places the United States among the countries expected to experience additional heat-related deaths during the current El Niño.
The original analysis estimates around 3,500 additional deaths in the United States over the period covered by the projection.
However, the greatest projected numbers are concentrated in countries and regions where populations can have fewer resources available to cope with prolonged extreme heat.
Why Extreme Heat Can Be So Dangerous
Extreme heat is often less visible than hurricanes, floods or earthquakes, but it can place enormous stress on the human body.
During very hot conditions, the body must work harder to maintain a safe internal temperature.
Heat exposure can contribute to:
- Heat exhaustion
- Heatstroke
- Dehydration
- Cardiovascular stress
- Kidney problems
- Respiratory complications
- Worsening of existing health conditions
The danger can become particularly serious when high temperatures continue overnight, preventing the body from recovering from daytime heat.
Researchers also point out that heat-related deaths can be difficult to identify and count accurately. In many cases, heat may contribute to a person’s death without being recorded as the direct cause.
The 451,000 Figure Is a Projection — Not a Confirmed Death Toll
One of the most important points about the new report is its scientific status.
The 451,000 figure is a modelled estimate, rather than a confirmed prediction of exactly how many people will die.
The report has not yet undergone peer review.
However, the researchers say the analysis uses methods that have previously been published and peer-reviewed, combining established relationships between temperature and mortality with seasonal temperature forecasts.
Raquel Nunes, an associate professor of health and environment at the University of Warwick who was not involved in the report, said the estimate is plausible as a modelling exercise but should not be treated as a definitive prediction.
The value of the analysis, she said, is in demonstrating the potential scale of the problem and highlighting the need for preparation.
Researchers Say There Is Still Time to Save Lives
The Climate Impact Lab says the report was released before peer review because the El Niño event is developing rapidly.
Researchers argue that waiting until the complete peer-review process is finished could mean missing an important opportunity to prepare communities before the worst heat arrives.
The analysis identifies areas where governments and health authorities could focus resources to reduce the number of deaths.
Potential measures include:
- Early heat-warning systems
- Public health heat-action plans
- Cooling centres
- Hydration facilities
- Improved emergency response
- Additional healthcare capacity
- Protection for outdoor workers
- Targeted assistance for vulnerable communities
- Public information campaigns about heat risks
The researchers say targeted action could potentially prevent tens of thousands of deaths during the current event.
Why Vulnerable Communities Face Greater Risks
Heat does not affect everyone in the same way.
People living in poorer communities may have fewer options for protecting themselves from dangerous temperatures.
For example, a household without reliable electricity or air conditioning may struggle to remain cool during prolonged heat.
Outdoor workers can also face several hours of direct exposure during the hottest parts of the day.
Other groups that can be particularly vulnerable include:
- Older people
- Young children
- People with limited access to healthcare
- Outdoor workers
- People living in poorly ventilated housing
- People without access to reliable cooling
- Communities affected by poverty or inadequate infrastructure
This means that the impact of El Niño is not simply a question of temperature. It is also closely connected to healthcare, infrastructure, income, housing and preparedness.
El Niño Could Also Bring Floods, Droughts and Wildfires
Heat is only one part of the potential problem.
A very strong El Niño can dramatically alter rainfall patterns across different parts of the world.
That means some areas could experience severe drought while others face unusually heavy rainfall and flooding.
Researchers warn that the current event could therefore contribute to several types of climate-related hazards, including:
- Extreme heat
- Drought
- Flooding
- Wildfires
- Water shortages
- Agricultural disruption
The projected 451,000 heat-related deaths do not represent the total potential human impact of the El Niño event. Other extreme weather events could create additional losses and disruption.
WMO Warns El Niño Could Remain Strong Into 2027
The World Meteorological Organization has independently warned that the current El Niño is likely to remain an important influence on global weather patterns into early 2027.
In its September update, the WMO said there was a nearly 100% likelihood of El Niño continuing through February 2027.
The organisation also forecast that the event could strengthen to a very strong intensity before reaching its peak towards the end of 2026.
This does not mean every country will experience the same weather.
El Niño influences different regions in different ways, and other climate patterns can strengthen, weaken or alter its effects.
A Warning About the Future of Extreme Heat
Perhaps the most significant message from the analysis is not simply what could happen this winter, but what the event may tell us about the future.
Researchers describe the unusually hot conditions as a “postcard from our future” because temperatures associated with this El Niño could resemble conditions expected to become more common as the planet continues to warm.
That raises an important public-health question.
If extreme temperatures that are currently considered exceptional become increasingly common, governments may have to move beyond temporary emergency responses and invest in long-term adaptation.
This could involve:
- Better urban planning
- More trees and shaded public spaces
- Heat-resistant buildings
- Improved public healthcare
- Reliable access to cooling
- Stronger early-warning systems
- Better protection for outdoor workers
- Climate-resilient infrastructure
Scientists Say Preparation Could Make a Difference
The 451,000 figure may sound overwhelming, but researchers emphasise that the purpose of the analysis is not simply to describe a future disaster.
It is intended to help authorities identify where action could have the greatest impact.
Climate Impact Lab researchers say better targeting of emergency resources could save many lives during the current El Niño.
But they also warn that societies cannot remain permanently in emergency mode.
As the planet warms, extreme temperatures that were once rare could occur more frequently, making long-term preparation increasingly important.
What Happens Next?
Scientists will continue monitoring the strength and development of El Niño over the coming months.
The Climate Impact Lab also plans to update its projections as new weather information becomes available.
For governments and health authorities, the immediate priority is preparing for periods of dangerous heat while strengthening systems that can protect people in the longer term.
The current projections should therefore be understood as a warning signal rather than a fixed prediction.
The actual number of heat-related deaths will depend on how temperatures develop, how long the event lasts, local weather conditions and how effectively governments and communities respond.
Key Facts at a Glance
| Key detail | What researchers say |
|---|---|
| Current climate pattern | Strong El Niño |
| El Niño began | June 2026 |
| Projection period | June 2026–February 2027 |
| Projected additional heat deaths | About 451,000 |
| Projected additional deaths Sept 2026–Feb 2027 | About 239,000 |
| Projected increase in extreme hot days | About 44% |
| Projected land temperature increase | About 1.2°C above normal |
| Country with largest projected toll | Nigeria |
| Projected additional deaths in Nigeria | About 31,400 |
| Projected additional deaths in India | About 15,800 |
| Projected additional deaths in Brazil | About 13,300 |
| WMO outlook | El Niño likely to persist through February 2027 |
These are modelled estimates and forecasts, not confirmed future death counts.
Final Thoughts
The new Climate Impact Lab analysis presents a serious warning about the potential human cost of an exceptionally strong El Niño.
Its estimate of 451,000 additional heat-related deaths by February 2027 should not be interpreted as a certainty. It is a modelling projection based on expected temperature changes and established relationships between heat and mortality.
Nevertheless, the scale of the estimate highlights why extreme heat is increasingly being treated as a major public-health threat.
With El Niño expected to remain in place into early 2027, governments still have an opportunity to strengthen heat warnings, provide cooling and hydration facilities, protect vulnerable people and improve emergency healthcare.
At the same time, the event offers a wider lesson about climate change: temperatures that currently appear exceptional could become much more familiar in the decades ahead.
The question, researchers say, is not only how much hotter the world may become, but how well communities prepare for it.
Sources and References
- University of Chicago – Institute for Climate and Sustainable Growth / Climate Impact Lab: Analysis projecting more than 451,000 additional heat deaths associated with the current El Niño.
- UC Berkeley Agricultural & Resource Economics: Report details, regional projections and comments from co-author Tamma Carleton.
- World Meteorological Organization (WMO): September 2026 El Niño update and forecast for persistence into February 2027.
- Scripps News: Independent reporting on the Climate Impact Lab projection and its scientific limitations.
- CNA: Regional projections for the Sahel, Indonesia and Southeast Asia.
- Down To Earth: Analysis of projected impacts in India and the wider September 2026–February 2027 period.
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