Ammon News - India has been sweltering through a baking hot summer, with temperatures in the northern state of Uttar Pradesh creeping past 48°C in May.

A recent study underlines the dangers of these worsening highs. It estimates that a single day of extreme heat causes approximately 3,400 excess deaths nationally in India.

A five-day heatwave is linked to nearly 30,000 extra deaths, according to the paper published in the Frontiers in Environmental Health journal last month.

These heatwaves are becoming more frequent, longer and more intense as climate change – driven by the burning of fossil fuels – pushes global temperatures higher. The past 11 years, from 2015 to 2025, were the hottest on record, according to the World Meteorological Organization (WMO).

Official counts of heatwave deaths in India are much lower – between 500 and 1,500 annually nationwide – but experts warn these are grossly underestimated. This is due to a lack of uniform tracking and a failure to take indirect impacts into account, such as the exacerbation of underlying health conditions.

The study is the first to attempt to rectify this by providing detailed numbers for all of India’s 765 districts. It also captures the full hidden impact of heat by taking into account all excess deaths during a heatwave, rather than only those directly attributable to heatstroke or heat-related disasters.

In the absence of uniform, countrywide data, the researchers looked at past data from 10 Indian cities in different climate zones on excess death rates during heatwaves. They matched each of India’s 765 districts to the city with the most similar climate, to estimate how many extra deaths would occur during hot periods.

India’s meteorological department declares a heatwave when temperatures reach 40°C or more in the plains, or at least 30°C in hilly regions. To qualify, these maximums must also be at least 4.5°C higher than the region’s normal average for at least two consecutive days.

Adding up all the districts to get national and state totals, the researchers found that just one extremely hot day is linked to about 3,400 extra deaths across India. A five-day heatwave is linked to roughly 30,000 extra deaths.

The biggest impacts are in states like Uttar Pradesh, which alone accounts for approximately 8,100 excess deaths during a five-day heatwave. Individual districts such as Ahmedabad, Jaipur and Surat each exceeded 250 excess deaths in a single event.

These findings are still described as conservative estimates, as they rely on historical temperature baselines and extrapolation from urban data. Rising temperatures, combined with the particular vulnerabilities of rural areas – outdoor work, less access to air-conditioning and medical care, higher rates of poverty and existing health conditions – likely mean the true numbers are higher.