A new forecasting tool estimates that an additional 370,000 people could die from extreme heat over the next six months as a strengthened El Niño pattern grips the planet.
The El Niño Heat Mortality Tracker, built by the Climate Impact Lab, also calculates that 484,500 heat-related deaths have already occurred since June 2026. Global warming is amplifying the weather phenomenon’s lethal effects beyond earlier projections.
Professor Michael Greenstone, co-founder of the Climate Impact Lab at the University of Chicago, said the tracker gives authorities a way to spot vulnerable populations before more lives are lost.
“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?” he said.
Nigeria is projected to suffer the highest death toll in the coming six months, with approximately 56,000 fatalities forecast. India and Brazil are also expected to rank among the hardest-hit nations, with the three countries together accounting for more than a third of all projected deaths by March 2027.
India has already borne especially devastating losses. The tracker attributes more than 100,000 deaths to extreme heat in that country alone since the current El Niño cycle began.
Other nations have recorded substantial tolls in the same period. China has seen an estimated 85,400 additional deaths, Sudan 38,500, and Indonesia more than 20,000.
The danger extends well beyond tropical and equatorial regions. In Europe, the tracker projects another 7,200 heat-related deaths in Italy, 4,800 in France, 2,500 in Germany and 2,300 in Spain. Rome, Barcelona, Seville and Malaga are among the cities forecast to face further fatalities as elevated temperatures persist.
The United States is expected to escape the worst global impacts, though California alone could see approximately 2,000 additional heat-related deaths.
A separate projection cited by the researchers puts the total El Niño death toll even higher, estimating 857,400 additional heat-related deaths between June 2026 and March 2027. That revised figure exceeds an earlier estimate by more than 350,000, driven by hotter-than-expected conditions during August and September.
The World Meteorological Organization has warned that the developing event is becoming “unprecedented in strength.”
El Niño develops when sea surface temperatures rise unusually in the equatorial Pacific, disrupting typical weather patterns worldwide. Depending on the region, this can produce prolonged drought, flooding, heavier rainfall, and sustained periods of extreme heat.
Scientists say the tracker could help governments and aid organizations channel resources toward communities facing the gravest danger. Recommended measures include early-warning systems, expanded healthcare access, reliable water supplies, and cooling centers. The projections highlight how unevenly extreme heat consequences may be distributed, with countries already experiencing high temperatures facing mounting risks in the months ahead.
The Climate Impact Lab is continuing to refine its mortality forecasts as the El Niño event progresses.