‘A calamity’: Why is a record heatwave sweeping South Asia?

A record-breaking, deadly heatwave sweeping South Asia has pushed temperatures to dangerous highs, disrupting daily life for hundreds of millions and raising new concerns about the vulnerability of one of the world’s most densely populated regions.

Countries including India, Pakistan and Bangladesh have seen temperatures soar well above seasonal averages, with some areas approaching or exceeding 45-50 degrees Celsius (113-122 degrees Fahrenheit).

In Pakistan, at least 10 people were reported to have died from heat-related complications on Tuesday, according to local emergency services, while multiple deaths related to the heat have also been reported in neighbouring India.

Such conditions are not entirely new in the region, as heatwaves have become a regular feature of South Asia’s pre-monsoon summer. However, scientists and meteorological agencies say the intensity, duration and geographic spread of recent heat events are unprecedented.

Increasingly, experts are linking these extremes to human-driven climate change, which is causing extremes in natural weather patterns.

As governments scramble to respond, the crisis is exposing deep inequalities across the region – determining who bears the greatest burden, and who is most able to withstand it.

What is causing heatwaves so early in the year?

India is experiencing an “unusually early and intense heatwave”, Anjal Prakash, research director at the Bharti Institute of Public Policy think tank in India, told Al Jazeera.

“High-pressure systems dominate, trapping hot air near the surface like a dome, preventing it from rising and cooling,” Prakash explained.

“This sinking air compresses, warms adiabatically, and blocks clouds, allowing relentless solar heating.”

He added that several factors relating to the climate are also contributing to the heat. “Weak pre-monsoon rains and lingering El Nino-like patterns further suppress cooling,” Prakash said.

El Nino develops when sea surface temperatures in the eastern Pacific Ocean, particularly off the western coast of South America, “become significantly warmer than usual”, often alongside a “falter” in easterly trade winds from the Americas to Asia, according to NASA. In contrast, the La Nina climate pattern tends to have a mild cooling effect on global temperatures.

The World Meteorological Organization, the United Nations’ weather and climate agency, said El Nino conditions could potentially form as early as the period from May to July.

“After a period of neutral conditions at the start of the year … there is high confidence in the onset of El Nino, followed by further intensification,” WMO chief Wilfran Moufouma-Okia warned last month.

The WMO added that while there is no evidence that climate change is increasing the frequency or intensity of El Nino events, it can worsen their impact.

An Indian worker rests on scaffolding as a taxi drives by near a market during a hot afternoon in Kolkata, India, May 6, 2026 [Piyal Adhikary/EPA]

Which countries are most affected by the heatwave?

India

The India Meteorological Department (IMD) has forecast higher-than-average temperatures across much of the country, warning that severe heatwave conditions in western regions and along the coast are expected this month.

Heatwaves are likely to be more frequent than usual along the eastern coast, in parts of the Himalayan foothills, and in the western states of Maharashtra and Gujarat, it said.

“There will be an increased number of heatwave conditions along the east coast states and Gujarat by about four to five days into the month of May,” IMD chief Mrutyunjay Mohapatra said, adding that temperatures in some areas could rise between three and five degrees Celsius (5.4 and nine degrees Fahrenheit) above normal.

In parts of northwestern and central India, temperatures have exceeded 46C (114.8) in some areas. In Maharashtra, the cities of Akola and Amravati recorded 46.9C (116.4F) and 46.8C (116.2) on April 26. Local media also reported that more than 90 of the world’s hottest cities were in India on April 24.

Multiple deaths have been recorded since the onset of extreme heat conditions. In the last week of April, two school teachers died of heatstroke, and four other people were reported to have died in the eastern state of West Bengal due to heat-related causes, Indian media outlets reported.

Pakistan

India’s western neighbour is also facing a heatwave crisis, with authorities warning it could last several days.

On Saturday, the Pakistan Meteorological Department (PMD) forecast continued heatwave conditions across the central and upper parts of the province of Sindh, and urged citizens to “avoid exposure to direct sunlight during the daytime and remain hydrated”.

In Karachi, the country’s most populated city, temperatures reached 44C (111F) on Monday this week – the highest recorded there since 2018, according to the PMD. At least 10 people were reported to have died on Tuesday, local emergency services said, when the extreme heat gripped the city.

Sindh cities of Jacobabad and Sukkur are expected to see temperatures as high as 46C (114.8F) later this week.

A volunteer sprays water on people as refreshment during a heatwave in Karachi, Pakistan [Rehan Khan/EPA]

Bangladesh

Bangladesh’s capital. Dhaka, as well as its districts of Faridpur, Rajshahi and Pabna, were particularly badly affected in mid to late April, recording temperatures between 37C (98.6F) and 38C (100.4F).

Temperatures have been rising in Bangladesh for some time. In 2024, authorities reported 24 heatwave days in April, the most in 75 years – with temperatures of greater than 40C (104F) in some districts – surpassing the previous record of 23 days in 2019.

What impact is the heatwave having on people in the region?

Kartikeya Bhatotia, research fellow at Harvard University’s Mittal South Asia Institute, said extreme heat affects people across “multiple pathways”, but that its impacts are deeply unequal.

“The most direct harm is physiological: heat stress overwhelms the body’s thermoregulatory capacity, leading to cardiovascular strain, kidney injury, disrupted sleep, and worsening of chronic conditions including diabetes, respiratory illness, and mental health conditions,” Bhatotia told Al Jazeera. “The elderly, pregnant women, young children, and those with pre-existing conditions face the greatest risk.”

Part of the problem is “structural”, he said – and low-income labourers are also more likely to be exposed.

“Those in poorly insulated, ill-ventilated homes face higher heat stress than those with access to cooling, and are often the same people who must toil outdoors.”

“Roughly 380 million Indians, about three-fourths of the workforce, are engaged in heat-exposed labour. Lost working hours erode piece-rate and daily wages, with downstream effects on nutrition and medication access that accumulate across the heat season and are rarely attributed to heat directly.”

How are governments responding to the heatwaves?

Bhatotia said India’s widely praised “heat preparedness model” is falling short of protecting its most vulnerable populations, as extreme temperatures intensify across the country.

“India is a pioneer in Heat Action Plans, city-level roadmaps combining early warning systems with water provision, cooling centres, public messaging and mandatory rest breaks,” Bhatotia said.

“These save lives, but tend to reach those already within formal systems.” He warned that “informal workers and daily-wagers – the most exposed – fall largely outside the protections such plans are designed around, and implementation is rarely tracked or enforced.”

According to Bhatotia, addressing the crisis requires a far broader “structural response” which “must span every level of government and its domains – housing, urban planning, health systems, labour protections and disaster management”, he said. He stressed that “health systems need expanded infrastructure, a trained workforce and functional surveillance so that heat-related morbidity and mortality are actually counted”.

Long-term resilience against rising temperatures will depend on systemic reforms being implemented, he added. “Building codes need to mandate passive design standards before structures are built,” while “labour protections must be made enforceable for informal workers”. Without such changes, he warned, heat risks will continue to outpace current response efforts.

Across the border in Pakistan, Islamabad-based climate expert and academic Fahad Saeed has raised concerns about the country’s preparedness and transparency in the face of intensifying heatwaves. He pointed to historical discrepancies between official figures and on-the-ground reality, citing the example of Karachi and the heatwave crisis there over the past decade.

“It is imperative for the government to, first of all, give the correct numbers, collect the real data, and then let the world know that it is a calamity,” he told Al Jazeera.

He attributed the underreporting partly to governance concerns, suggesting authorities may be downplaying the crisis to avoid political fallout.

However, Saeed stressed that acknowledging the scale of “loss and damage” is critical – not only to mobilise public awareness but also to access international climate funds and develop effective response systems. Without accurate data, he warned, meaningful adaptation measures will remain out of reach.

“Putting the dust under the carpet is no solution,” he said. Without confronting the true scale of loss, “it will be super-difficult to develop any kind of countermeasures.”

Will heatwaves get worse in the future?

Yes.

“Climate models project that both the frequency and intensity of extreme heat events will increase across South Asia over the coming decades, even under moderate emissions scenarios,” Harvard’s Bhatotia said.

While India has warmed more slowly than the global average in recent decades, Bhatotia said this is partly due to temporary cooling effects from aerosol pollution and widespread irrigation.

“Both of these are likely to weaken in the coming years, potentially accelerating warming beyond what the historical record would suggest,” he added.

However, he stressed that rising temperatures do not necessarily mean rising harm if the correct measures are implemented.

“Good adaptation planning, anticipatory action, and early warning systems linked to pre-authorised response can substantially reduce damage even as temperatures rise,” he said, adding that “the goal is to decouple the trend in heat from the trend in suffering”.