El Niño could cause an additional 451,000 heat-related deaths by February 2027

The ongoing “super El Niño” could lead to an additional 451,000 heat-related deaths worldwide between June 2026 and February 2027, according to a projection published on Wednesday, September 23, by the Climate Impact Lab at the University of Chicago.

The study estimates that the number of extreme heat days will increase by 44% compared to a normal year. For the six-month period from September 2026 to February 2027, the additional toll is projected to be 239,000 deaths, with a margin of uncertainty of 11,000.

The Global South is expected to bear the brunt of the risk. Nigeria is projected to lead with 31,400 additional deaths between September and February, followed by Indonesia with 19,300 and Sudan with 17,500. Niger and Chad are expected to record 10,000 and 8,000 additional deaths, respectively. In Asia, where drought linked to El Niño is already threatening crops, the Philippines, Vietnam, Thailand, and Cambodia are projected to total 19,400 additional deaths.

The World Meteorological Organization considers the persistence of El Niño until February 2027 to be almost certain and anticipates its further strengthening. The World Health Organization ranks heat stress among the very high risks associated with the phenomenon, alongside cholera and malnutrition in areas affected by droughts or floods.

These figures remain projections, not observed outcomes. The Climate Impact Lab applied seasonal forecasts from the European Centre for Medium-Range Weather Forecasts to 24,378 regions, comparing them to the 1996-2025 average. Full details of the methodology are yet to be published in a peer-reviewed scientific journal.

The lab indicates that heat alert systems, cooling centers, access to water, worker protection, and strengthening hospital capacities can help reduce the number of deaths in the most exposed areas.