‘Too hot, too humid’: Researchers break down the deadly 2026 South Asia heatwave

By A Representative 

According to a new analysis, a relentless heatwave that began in mid-April has pushed temperatures in India and Pakistan above 46°C in many areas, running 5–8°C above seasonal norms. The combination of extreme heat and high humidity, three resesrchers writing in The Conversations warn, is creating dangerously lethal conditions across the subcontinent.

At least 37 people have died in India and 10 in Pakistan, though the authors note these figures are “likely to be a major underestimate” as heat-related deaths are systemically undercounted in the region.

Why this heatwave is different

The researchers -- Andrew King, Senior Lecturer in Climate Science at The University of Melbourne; Mika Peace, a Heatwave Research Scientist at The University of Adelaide; and Sana Mahmood, a Research Associate in Climate Science at The University of Melbourne -- explain that persistent high-pressure weather systems have suppressed cloud formation and rainfall, trapping hot air near the surface. 

Drying soils have worsened the effect, as less energy goes into evaporating moisture and more goes into heating the land. Meanwhile, record electricity demand for air conditioning is straining grids.

Urban areas are especially dangerous: concrete and asphalt absorb heat by day and release it slowly at night, keeping cities hotter overnight and denying people relief.

The humidity factor

Humidity makes heat far more lethal, the researchers write. The human body relies on sweat evaporation to cool down, but humid air slows evaporation. Core body temperature can rise past 40°C, triggering heatstroke that damages the brain and vital organs.

They note that scientists now know lethal combinations occur across a range of temperatures and humidity levels. For older people outdoors, 35°C with 90% humidity is as deadly as 45°C with 30% humidity. Even healthy 18–35 year olds face risk at 45°C and 40% humidity – levels likely already reached during this event.

Climate change link

The authors cite estimates from World Weather Attribution: the first major heatwave from 15–29 April 2026 was made about three times more likely and about 1°C hotter due to climate change. Under current global warming of ~1.4°C, such events now occur roughly once every five years. If warming reaches 2.6°C by 2100, similar heatwaves would hit every 2–3 years and be 2.2°C hotter.

Unequal threat

Wealthier people can turn on air conditioners, but King, Peace, and Mahmood note that poorer communities in informal settlements cannot escape. Outdoor workers – farmers, construction workers, delivery riders – face the highest risks. Rural areas suffer too, with more outdoor labour, limited cooling, and healthcare far away.

Relief ahead?

The monsoon typically arrives in early June in southern India, covering the whole country by mid-July, and reaches Pakistan in early July. Cloud cover and rainfall will lower daytime temperatures, though humidity often remains high.

“Relief can’t come too soon for the region,” the authors conclude, “but as climate change ramps up, extreme heat and humidity will hit these nations more often – and more severely.”