According to a new report by the Climate Impact Lab, the number of extremely hot days is expected to increase by 44% compared with normal years.
Nigeria is projected to record the highest number of excess heat-related deaths, with an estimated 31,400 fatalities between September 2026 and February 2027. Indonesia is expected to record 19,300 additional deaths, followed by Sudan with 17,600.
The researchers estimate that extreme heat across Africa’s Sahel region, including Niger, Chad, Nigeria and Sudan, could result in an additional 66,800 deaths during the six-month period.
The Philippines, Vietnam, Thailand and Cambodia are collectively projected to see around 19,400 additional deaths.
Researchers warned that the number of excess deaths could rise further if El Niño continues into 2027. They said parts of the Northern Hemisphere, including India and Pakistan, could be particularly vulnerable during the summer months.
The Climate Impact Lab described this year’s El Niño as a "postcard from the future", saying it could bring temperatures that may become normal in the coming decades.
The researchers called for emergency response efforts to focus on high-risk regions to reduce heat-related deaths in the coming months.
Michael Greenstone, an economist at the University of Chicago and co-founder of the Climate Impact Lab, said the report identifies areas where emergency action can be taken now to potentially save tens of thousands of lives.
