Scientists are warning that an unusually strong El Niño could intensify global heat and increase the risk of heat-related deaths in vulnerable regions over the coming months.
A new analysis from the Climate Impact Lab projects that the current El Niño could contribute to an estimated 451,000 additional heat-related deaths between June 2026 and February 2027 compared with a normal year. The estimate is based on modelling and should not be interpreted as a confirmed death toll.
The researchers also estimate that global land temperatures could average about 1.2 degrees Celsius above normal during the period covered by their projections, with the number of extremely hot days increasing by about 44% compared with a typical year.
Nigeria among countries facing high projected risks
The analysis identifies countries in the Global South as particularly exposed to the additional heat.
Nigeria is projected to experience one of the largest national impacts, with about 31,400 additional heat-related deaths estimated over the period covered by the study. The Sahel region as a whole is projected to account for about 66,800 additional deaths, with Sudan, Niger and Chad also among the countries facing substantial projected impacts.
These figures are modelled estimates rather than observations.
The researchers calculated excess mortality by comparing projected temperatures during the El Niño period with mortality expected under average conditions. Their analysis incorporated historical relationships between temperature and mortality across 24,378 regions, together with seasonal temperature forecasts.
What is El Niño?
El Niño is a recurring climate pattern associated with unusually warm ocean temperatures in the central and eastern tropical Pacific.
Changes in Pacific Ocean temperatures can alter atmospheric circulation and rainfall patterns far beyond the Pacific region.
The effects vary geographically. Some areas can experience unusually hot and dry conditions, while others may face heavier rainfall, flooding or changes in storm patterns.
The current event has been described by researchers and forecasters as an unusually strong or “super” El Niño because of the scale of the Pacific warming.
Why this event is different
The current El Niño is developing against a much warmer global climate baseline.
The World Meteorological Organization said in September that El Niño’s effects are occurring on top of an already warming planet. The organisation noted that the past seven years have been the warmest on record and that recent months have included record-breaking heat in different parts of the world.
Scientists therefore expect the combination of natural El Niño warming and the existing long-term warming trend to produce unusually high temperatures in many regions.
Climate Impact Lab researchers described the projected conditions as resembling temperatures that climate change models otherwise project for roughly two decades from now.
Heat risk is not distributed evenly
The projected effects vary substantially between regions.
The Climate Impact Lab estimates that the Sahel could experience about 66,800 additional heat-related deaths during the study period.
Southeast Asian countries including the Philippines, Vietnam, Thailand and Cambodia are also projected to experience significant additional mortality, while Indonesia, India and Brazil are among other countries identified as having high projected impacts.
The differences reflect variations in climate, population exposure, age structures, existing health vulnerabilities and the ability of communities to respond to extreme heat.
The health effects go beyond temperature
Extreme heat can place substantial stress on the cardiovascular and respiratory systems, particularly among older people and those with existing health vulnerabilities.
Heat can also increase pressure on healthcare systems and create additional risks for people who work outdoors.
The effects of El Niño are not limited to heat.
Changes in rainfall can contribute to drought in some regions and flooding in others. The current event has already been associated with concerns over wildfires, agricultural disruption and water availability in different parts of the world.
Nigeria faces a particular exposure
Nigeria’s projected position in the Climate Impact Lab analysis is significant because of its location in the Sahel and its large population.
The report estimates about 31,400 additional heat-related deaths in Nigeria during the period examined.
That figure should be treated as a risk estimate rather than a forecast of an inevitable outcome. The researchers specifically argue that targeted preparation can reduce heat-related mortality.
For Nigerian communities, the implications could include increased pressure on health services, greater risks for outdoor workers and additional challenges in areas already exposed to high temperatures.
The timing of the projected heat also matters. Some of the largest effects are expected later in the forecast period, meaning preparedness measures could still influence the eventual health impact.
Scientists say preventive measures can save lives
The Climate Impact Lab says governments and humanitarian organisations can use regional forecasts to direct resources toward areas facing the greatest heat risks.
Measures identified by the researchers include heat-warning systems, cooling centres, hydration facilities, health outreach and additional protection for outdoor workers.
Expanding healthcare capacity during periods of extreme heat is another measure highlighted in the report.
The World Meteorological Organization has similarly emphasised the importance of heat preparedness, particularly in cities where high temperatures can affect homes, workplaces, schools and hospitals.
The 451,000 figure has important limitations
The headline figure requires careful interpretation.
The Climate Impact Lab estimates 451,000 additional heat-related deaths from June 2026 through February 2027 compared with a normal year. It is therefore a modelled estimate of excess mortality associated with the projected temperature conditions, rather than a prediction that exactly 451,000 people will die.
The researchers also estimate that about 239,000 of those additional deaths could occur between September 2026 and February 2027, with an uncertainty range of approximately 11,000 deaths.
The methodology is not yet published in a peer-reviewed journal. Climate Impact Lab says its analysis combines temperature-mortality relationships across thousands of regions with seasonal forecasts and that the methodology will be published for peer review.
These limitations mean the figures should be understood as projections intended to identify potential risks and guide preparation.
El Niño could continue into 2027
The World Meteorological Organization has warned that the strongest effects of the current El Niño are still ahead.
Current forecasts indicate that the event could persist through the Northern Hemisphere winter and potentially into spring 2027.
The Climate Impact Lab says heat-related effects could also continue after the initial forecast period if the El Niño persists.
That would increase the importance of monitoring temperatures, rainfall and public-health conditions as the event develops.
A warning for governments and communities
The latest research does not establish a predetermined global death toll.
Instead, it highlights the potential scale of the health risks associated with an exceptionally strong El Niño occurring on top of an already warmer climate.
For Nigeria and other vulnerable countries, the projected figures underscore the importance of heat monitoring, early warnings, healthcare preparedness and protection for people exposed to high temperatures.
The coming months will provide new observations that can be compared with the current forecasts. Those observations will help determine how closely the developing El Niño follows the current projections.
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