Fifty-seven percent of the districts in India are now facing extreme heat risks, showed a new study published by the Council on Energy, Environment and Water on Tuesday.

These districts are home to 76% of the country’s population.

The study by the Delhi-based not-for-profit think tank and policy institution found that the 10 states and Union Territories most prone to heat risk were Delhi, Andhra Pradesh, Goa, Kerala, Maharashtra, Gujarat, Rajasthan, Karnataka, Tamil Nadu and Uttar Pradesh.

It assessed heat conditions in 734 districts using 35 indicators to track how climate change reshaped heat risks between 1982 and 2022.

Four hundred and seventeen of these districts were in the “high to very high risk” extreme heat categories. These included some rural districts in Bihar, Kerala, Maharashtra and Uttar Pradesh, which have a large number of outdoor agricultural workers, according to the study.

Two hundred and one districts faced moderate risk, the study showed.

Even though the remaining 116 districts were in the low-risk category, they were only relatively less exposed and were not immune to the problem, the study found.

The study found three trends. There was an alarming rise in very warm nights, increasing relative humidity in northern India – particularly in the Indo-Gangetic plain – and more intense heat exposure in dense, urban and economically-critical areas such as Delhi, Mumbai, Ahmedabad, Hyderabad, Bhopal and Bhubaneswar.

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Warmer nights

About 70% of the districts had faced more than five additional “very warm nights” each summer between 2012 and 2022, as compared to the climatic baseline between 1982 and 2011, the study found.

“Very warm nights” refer to nights where the temperature stays unusually high, or warmer than what used to be normal 95% of the time in the past.

By contrast, only about 28% of the districts faced a similar increase on “very hot days”.

The warmer nights were rising faster than hot days, the study found. This makes it more difficult for the human body to cool down and recover from the heat faced during the day.

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Relative humidity rising in northern India

The relative humidity had increased by up to 10% in the Indo-Gangetic plain over the last decade, the study found.

While coastal areas typically record 60% to 70% relative humidity, North India had historically experienced levels of about 30% to 40%. However, over the past decade, this increased to 40% to 50%, the study noted.

Arunabha Ghosh, the think tank’s chief executive officer, said that heat stress was no longer a “future threat – it’s a present reality”.

“Increasingly erratic weather due to climate change – record heat in some regions, unexpected rain in others – is disrupting how we understand summer in India,” said Ghosh. “But the science from the study is unequivocal: we are entering an era of intense, prolonged heat, rising humidity, and dangerously warm nights.

Ghosh added: “We must urgently overhaul city-level Heat Action Plans to address local vulnerabilities, balance emergency response measures with long-term resilience, and secure financing for sustainable cooling solutions.”

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