India could see 55,000 additional heat-related deaths between October 2026 and March 2027, according to new projections.
The global death toll linked to super El Niño could reach 857,000 by March 2027.
Nigeria and India face the highest projected mortality over the next six months, with most of India's deaths expected in March.
Researchers warn that such extreme heat could become commonplace within two decades.
India could see around 55,000 additional heat-related deaths over the next six months, between October 2026 and March 2027, with most projected to occur in March, according to updated estimates by the University of Chicago’s Climate Impact Lab, which warns that much of the mortality burden will fall on countries in the Global South.
The revised projections put India among the countries expected to suffer the highest heat-related mortality from the ongoing super El Niño, which is driving unusually high temperatures while also shifting rainfall patterns around the world.
This projected toll is substantially higher than the 15,800 additional heat-related deaths estimated for India in the lab’s September report, which covered September 2026 to February 2027.
The global estimate has also risen sharply. The updated projections estimate that extreme heat could result in around 857,000 additional deaths over the course of El Niño, between June 2026 and March 2027, up sharply from the 451,000 projected in the September report for June 2026 to February 2027.
The revised estimate reflects the addition of March to the projection period and the incorporation of observed temperatures for August and September, which were significantly warmer than forecast.
In fact, August was the warmest August and September the second warmest September on record, with global monthly average temperatures breaching 1.5 degrees Celsius (°C) for two consecutive months, according to the latest update from Copernicus Climate Change Service (C3S), implemented by the European Centre for Medium-Range Weather Forecasts.
The month was 0.11°C cooler than September 2023, making it the second-warmest on record.
Global average temperature for September 2026 was 16.27°C, which was 0.82°C above the average during 1991-2020 and 1.63°C above the pre-industrial (1850-1900) levels.
The updated heat mortality tracker projects around 373,000 additional heat-related deaths worldwide will occur between October 2026 and March 2027. Nigeria is expected to record the highest toll during this period, at around 56,000 deaths, followed closely by India, with approximately 55,000.
The report had warned earlier that the unusually high temperatures driving these deaths offer a glimpse of a much hotter future. The conditions expected during this El Niño resemble temperatures that climate change projections suggest could become normal and the scale of the mortality risk from these temperatures could become commonplace around 20 years from now.
Climate Impact Lab has launched El Niño Heat Mortality Tracker, which provides monthly projections of heat-related mortality up to six months ahead, alongside estimates of deaths since June 2026. The tool offers state-and provincial-level data worldwide to help policymakers, funders and humanitarian organisations identify high-risk regions and prioritise resources.
“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?” says Michael Greenstone, co-founder of the Climate Impact Lab and the Milton Friedman Distinguished Service Professor in Economics at the University of Chicago.
“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,” he says.