A report released Wednesday, Sept. 23, 2026, by the University of Chicago’s Climate Impact Lab estimates that the current El Niño climate pattern could result in 451,000 more heat-related deaths between June 2026 and February 2027 compared to a typical year. The research hub attributed the projected increase to hotter temperatures and shifting rainfall patterns associated with the phenomenon, which the World Meteorological Organization suggests could become the strongest on record.
El Niño is a climate pattern involving above-average ocean temperatures in the Pacific Ocean near the equator, which influences global weather. Researchers at the Climate Impact Lab reached their estimates by combining seasonal temperature forecasts and localized mortality data across 24,000 regions. The report indicates that global land temperatures during this period could be 1.2 degrees Celsius (2.1 degrees Fahrenheit) higher, resulting in 44% more extremely hot days than a normal year.
The greatest impact is forecast for the Global South. Researchers expect the Sahel region—including Nigeria, Sudan, Niger, and Chad—to record more than 65,000 combined heat-related deaths. In Southeast Asia, the Philippines, Vietnam, Thailand, and Cambodia are projected to see approximately 19,400 additional deaths, while Indonesia could see 19,300. India and Brazil are also identified as areas with projected tolls of 15,800 and 13,300, respectively. In the United States, the report estimates 3,500 additional heat deaths during the nine-month period, with the highest risk occurring in September 2026.
The report identifies specific populations at risk, particularly low-income residents in urban areas and those in developing nations. According to climate and law professor Sheila Foster, many heat-related deaths occur indoors among people who may have air conditioning but cannot afford the electricity costs to run it during heat waves. Globally, urban exposure to extreme heat has increased 200% since 1982, affecting approximately 1.7 billion people.
For individuals in the affected regions, the report noted that heat warnings, health outreach, the implementation of hydration stations, and the opening of cooling centers can help people cope. Outdoor workers may see new safety protections, while households in the Global South already facing food insecurity and high energy costs—exacerbated by climate change and the war in Iran—may experience further pressure. Michael Greenstone, co-founder of the Climate Impact Lab, noted that while the current El Niño is expected to end by February 2027, the heat effects could persist into the following summer.
Beyond immediate health risks, the climate phenomenon is expected to influence global markets. The reports indicate that El Niño-driven weather may lead to higher food prices, shipping delays, and supply chain disruptions. The World Meteorological Organization expects the phenomenon to reach its peak intensity near the end of 2026, while the U.S. Climate Prediction Center expects it to remain through the Northern Hemisphere winter and potentially into spring 2027. Researchers suggested that governments use the data to allocate emergency financing and expand hospital capacity before the heat peaks.