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

South Asia is enduring a searing and prolonged heatwave that has thrust daytime temperatures into the danger zone, straining health systems, disrupting livelihoods and exposing deep social inequalities across one of the world’s most densely populated regions.

A region on the boil

From India to Pakistan and Bangladesh, temperatures have surged well beyond seasonal norms, with multiple locations nearing or surpassing 45–50°C (113–122°F). In India’s northwest and central belt, thermometers have pushed past 46°C (114.8°F), and cities in Maharashtra recently touched the upper 46s. On a single day in late April, dozens of the world’s hottest cities were concentrated in India.

Pakistan’s largest metropolis, Karachi, hit 44°C (111°F)—its highest reading since 2018—while the Sindh cities of Jacobabad and Sukkur are bracing for highs near 46°C (114.8°F). Emergency services in Pakistan have reported heat-related deaths, and fatalities have also been registered in India amid the surge. Bangladesh, too, has faced an extraordinary April, recording more heatwave days than at any point in the past 75 years, with districts such as Dhaka, Faridpur, Rajshahi and Pabna repeatedly hovering around 37–38°C (98.6–100.4°F) and exceeding 40°C (104°F) in some locales.

Why it’s so extreme

Several factors are converging to drive this punishing spell. A dominant high-pressure “heat dome” is trapping hot air near the surface, forcing it to sink, compress and warm—while also suppressing cloud cover and rainfall. Weak pre-monsoon showers have offered little relief, and lingering El Niño-like conditions are helping tilt the atmosphere toward hotter-than-usual outcomes across the region.

Global warming is the force multiplier. Even when natural climate patterns such as El Niño ebb and flow, a steadily warming baseline increases the likelihood that heatwaves arrive earlier, last longer and cover more territory. Regional meteorological agencies have warned of higher-than-average temperatures persisting through May, with heatwave days increasing along India’s eastern coast, parts of the Himalayan foothills, and western states including Maharashtra and Gujarat. In some places, forecasters expect highs to sit 3–5°C (5.4–9°F) above long-term averages.

Who bears the brunt

Extreme heat harms the body through multiple pathways: it overwhelms the ability to cool via sweating, strains the cardiovascular system, increases risks of kidney injury and exacerbates chronic illnesses from diabetes to respiratory disease. The elderly, pregnant people, infants and those with pre-existing conditions face the steepest risks—especially when cooling and clean water are scarce.

But the burden is also structural. Millions of South Asians work outdoors or in poorly ventilated spaces—construction workers, street vendors, agricultural laborers—often without reliable access to shade, rest breaks or hydration. In India alone, hundreds of millions are engaged in heat-exposed occupations. Lost hours mean lost wages, and that spirals into reduced access to nutrition and medication, compounding the danger as heat persists through the season. Inadequate housing (thin roofs, no insulation, limited airflow) magnifies heat stress at night, preventing recovery and worsening next-day risk.

Preparedness—and its limits

Over the past decade, many cities have adopted heat action plans that combine early warnings, outreach, cooling centers, water distribution and work-rest scheduling. These efforts save lives. Yet implementation is uneven, and protections often miss the most exposed: informal and migrant workers, people outside formal employment systems, and residents of crowded informal settlements.

Experts say durable protection demands a whole-of-government approach. That includes enforcing labor safeguards such as mandatory rest and hydration breaks; upgrading health systems with surge capacity, heat illness training and real-time surveillance to actually count and respond to heat-related morbidity and mortality; and embedding passive cooling into building codes (shade, cross-ventilation, reflective or green roofs, thermal insulation) before structures rise.

Data, transparency and public trust

Accurate reporting of heat illness and fatalities is essential. Underreporting—whether from limited surveillance, fragmented data systems, or governance concerns—masks the scale of loss and slows effective response. Transparent accounting helps galvanize public awareness, guides targeted interventions and underpins access to climate adaptation finance. Without credible numbers, countermeasures remain under-resourced and misdirected.

What comes next

Climate models consistently project that South Asia will experience more frequent and intense heat extremes in the coming decades, even under moderate emissions scenarios. While parts of the subcontinent have historically warmed slightly more slowly than the global average—partly due to aerosol pollution and extensive irrigation that provide some temporary cooling—those buffers are likely to weaken, potentially quickening the pace of warming.

Yet rising temperatures do not have to translate into rising harm. Early warning systems linked to pre-authorized responses, neighborhood-level cooling access, better urban design (trees, shade, reflective materials), resilient power for fans and refrigeration, and enforceable protections for outdoor labor can dramatically reduce health impacts. Public messaging that reaches informal workers and peri-urban settlements—in local languages and through trusted channels—can ensure life-saving guidance actually reaches those most at risk.

The stakes this season

As the pre-monsoon heat intensifies, practical steps matter: rescheduling outdoor work to cooler hours, guaranteeing water and electrolyte access, opening libraries, schools or community halls as cooling shelters, and prioritizing check-ins for older adults and isolated residents. Power reliability and water supply are not just infrastructure issues—they are frontline health defenses.

This heatwave is a warning shot. Without swift structural reforms and sustained investment in resilience, each hot season will extract a heavier toll. With them, South Asia can decouple the trend in heat from the trend in suffering—even as the planet warms.