Global: A powerful El Niño event developing across the Pacific Ocean is raising concerns about an extended period of extreme heat, with new climate projections estimating that hundreds of thousands of additional deaths could occur worldwide as temperatures rise over the coming months.

A new assessment from climate researchers at the University of Chicago’s Climate Impact Lab estimates that the additional heat associated with the current El Niño could contribute to approximately 451,000 excess deaths between June 2026 and February 2027, compared with conditions expected during a normal year.

The projection is not a prediction that these deaths will necessarily occur. Rather, it represents an estimate of additional heat-related mortality based on projected temperature conditions and previously established relationships between extreme heat and mortality.

Researchers estimate that the number of extremely hot days could be around 44% higher than normal during the period affected by the event. The additional heat is expected to be particularly challenging for populations living in regions with limited access to cooling, healthcare and other protective infrastructure.

Africa Among the Most Exposed Regions

The Sahel is among the regions facing the largest projected increase in heat-related deaths. Researchers estimate approximately 66,800 additional deaths across the Sahel between September and February, with Nigeria, Sudan, Niger and Chad among the countries facing substantial projected impacts.

Nigeria alone is projected to experience around 31,400 additional heat-related deaths during that six-month period under the researchers’ model.

The potential impact is not limited to Africa. Indonesia, India, Brazil and several Southeast Asian countries are also identified among areas facing significant additional heat risks.

India and Southeast Asia Face Significant Heat Exposure

India is projected to experience approximately 15,800 additional heat-related deaths between September 2026 and February 2027 compared with a normal year, according to the assessment.

Indonesia is projected to face around 19,300 additional deaths, while the Philippines, Vietnam, Thailand and Cambodia together could see approximately 19,400 additional heat-related deaths under the model’s estimates.

The actual effects of El Niño vary considerably from one region to another. The climate pattern can influence not only temperatures but also rainfall, drought conditions, storms, wildfires and agricultural production.

El Niño Could Affect More Than Human Health

Extreme heat is only one part of the potential impact.

A strong El Niño can disrupt normal rainfall patterns over large areas, increasing drought risks in some regions while contributing to heavier rainfall and flooding elsewhere. Such changes can affect crops, water supplies, fisheries and food prices.

Parts of Southeast Asia are already experiencing pressure from reduced rainfall, falling water levels and wildfire activity. Scientists are therefore watching the event closely as it develops toward its expected peak later in the year.

Emergency Preparation Could Reduce the Impact

Researchers say the projections can help governments identify areas where preventive measures could save lives.

Heat-warning systems, access to cooling centres, medical preparedness, protection for outdoor workers and targeted assistance for vulnerable communities are among the measures that can reduce exposure during extreme heat.

The researchers describe the current event as an indication of the type of temperatures that could become more common in the future as the planet continues to warm.

Scientists will continue updating their estimates as atmospheric and oceanic conditions evolve. The eventual health impact will depend on how long the El Niño persists, how temperatures develop in individual regions and how effectively communities respond to periods of dangerous heat.