A prolonged heatwave across India is putting hundreds of millions of people at risk.
A prolonged pre-monsoon heatwave is sweeping across India and neighboring Pakistan, exposing hundreds of millions of people to dangerous conditions and raising fears of a rising death toll.
Temperatures have climbed above 46 degrees Celsius in many Indian cities since mid-April, according to the research group World Weather Attribution. The group reported that the extreme heat has strained agriculture, pushed up energy demand, and hit public health across two of the most densely populated regions on earth. India and Pakistan together host about 1.7 billion people.
At least 37 heat-related deaths have been reported in India so far this year, World Weather Attribution said, along with ten deaths recorded in Karachi. The group noted that outdoor activity has been the main risk factor. Researchers warn those figures are likely an undercount, as heat deaths are often missed in official tallies.
The danger this year is being driven not just by temperature but by humidity. The Carnegie Endowment for International Peace reported that India’s average relative humidity rose from 67.1 percent in the 2015 to 2019 period to 71.2 percent between 2020 and 2024. High humidity stops the body from cooling through sweat, which is its last line of defense.
Researchers have identified a wet-bulb temperature of 35 degrees Celsius as the point beyond which even a healthy adult resting in shade with water will face a fatal rise in core body temperature within hours, according to Carnegie. Air conditioning can remove both heat and moisture, but only 8 percent of Indian households have it.
India Heatwave Hits Vulnerable Groups Hardest
The people most at risk are the elderly, infants, outdoor workers, daily wage earners, and pregnant women, Carnegie reported. Early-onset heat is especially dangerous because the body has not yet adjusted to the season.
Past years show how deadly these events can be. In 2015, India and Pakistan recorded roughly 2,300 and 1,200 heat deaths respectively, according to World Weather Attribution. The 2025 heatwave killed at least 455 people in India, including deaths linked to associated storms.
The current spell has also driven record electricity demand as cooling needs surge, World Weather Attribution said. Agricultural drought has affected more than one million square kilometers, compounding risks to food production and livelihoods.
Authorities across the region have urged residents to stay hydrated, avoid the midday sun, and watch for signs of heatstroke. Officials say the months of May and June typically bring the most intense heat, leaving the most exposed populations facing weeks of continued strain.
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