How Many People Die in India From Hot Weather? Nobody Really Knows.

India is getting hotter, faster.

The grim present presages a grimmer future for the world’s most populous country, which is experiencing more frequent and severe heat waves. But India — with 1.4 billion people, many of whom are impoverished and particularly vulnerable to climate change — is yet to grasp the magnitude of the problem and may be underequipped to deal with it, public health experts and scientists say.

How Are Heat Deaths Counted?

The problem starts with counting. Heat-related deaths generally occur when a body overheats and cannot cool itself because the ambient temperature, including humidity, is too high. But many happen when an underlying illness reduces a person’s ability to cope with extreme heat. Numerous studies suggest that India undercounts such deaths. In part, that is because most government doctors follow a narrow definition of what classifies as a heat-related death, sticking to easily identifiable causes like heat stroke, experts say.

Government guidelines specify that to classify a death as heat-related, medical personnel should factor in high ambient temperatures and the circumstances under which a death occurred, even if the body temperature had been lowered by attempts to cool it down. The autopsy procedures laid out in the directive underscore that determining a heat-related death is an investigative examination, but that puts a time-consuming burden on India’s already stretched medical system.

Doctors in public hospitals are often overworked and “not well trained to identify cause of death,” said Dileep Mavalankar, director of the Indian Institute of Public Health Gandhinagar. And private hospitals, which provide a substantial amount of medical care in India, don’t record deaths as heat related.

The number of people who die from heat-related causes that were able to reach a health-care facility in time to be diagnosed accurately is a “very small percentage,” said Bhargav Krishna, an environmental health and policy researcher at the Sustainable Futures Collaborative, a research organization. This is another reason reported deaths from extreme heat do not reflect the actual number, Mr. Krishna said.

Last year, HeatWatch, an Indian nonprofit, found that figures released by the government for heat-related deaths were far lower than comparable deaths tallied in news reports; one reason is that different government agencies have different criteria and ways of counting. Between March and June of 2024, for example, newspapers reported 41 confirmed deaths in the state of Odisha; in July, India’s ministry of health and family welfare reported 26 deaths in the state in response to a question in Parliament, according to a HeatWatch report.

What do Studies Show?

Another way to tally heat deaths is through studies of mortality during periods of very hot weather, despite patchy data.

A 2024 study published in the journal Environment International found that there was a 14.7 percent increase in deaths on days it defined as “heat wave” days based on various calculations, compared to other days. The findings were based on average temperatures and deaths from all causes in 10 Indian cities over roughly a decade.

Building on that work, two researchers at the University of California, Berkeley found that five heat waves a year, each lasting five days, can lead to at least 150,000 excess deaths every summer across India.

The researchers also pointed out discrepancies in heat-related deaths reported by government agencies. India’s National Disaster Management Agency reported 17,706 heat wave deaths between 2000 and 2020; the India Meteorological Department recorded 10,545 deaths over the same period, the researchers said in an April 2025 article. They attributed the discrepancies between agencies partly to differences in methodology and data sources.

Many scientists are pushing for India to create a unified, digital database containing the granular city and district-level weather and mortality data needed to determine how heat waves affect sections of the population and what can be done to adapt.

What Is India Doing About It?

The India Meteorological Department labels a stretch of hot weather a “heat wave” when temperatures exceed normal temperatures within a certain band for a particular region, or when the maximum temperature exceeds 113 degrees. Either condition has to be met for at least two consecutive days before it can be called a heat wave.

Disaster agencies, government ministries and weather departments recognize that heat waves are a major public health problem, and that the country needs better tools to predict and manage extreme heat. Hundreds of cities and states have heat action plans, although experts say they are implemented unevenly. Awareness campaigns and advisories about how to cope with searing temperatures have helped people adapt their habits.

But experts say it’s not enough. After a climate conference organized in March by Harvard in partnership with the Indian government, the university issued a list of takeaways, including that the government must make forecasting more effective to improve preparedness. It said that health data collection in India remains fragmented and there is a need for more detailed information.

“Our current understanding of mortality and heat exposure at the city scale is crude,” the statement said, but there is enough information to “guide sensible public health decisions already.”