‘Completely Off the Scale’: As Heatwaves Grip India, New Studies Reveal a Planet in Peril 

‘Completely Off the Scale’: As Heatwaves Grip India, New Studies Reveal a Planet in Peril 

The central Indian state of Chhattisgarh has become the epicentre of an unprecedented pre-summer heat event, with temperatures breaching the 40°C mark in late March—a threshold that typically belongs to the brutal mid-summer months of May and June. 

In the Rajnandgaon district, mercury soared to 40.5°C on March 30, tying with Washim in Maharashtra for the highest temperature recorded in India’s plains this season. But the scorching conditions are not an isolated phenomenon. From the Rayalaseema region of Andhra Pradesh to the hill stations of Kerala, and from Telangana’s northern districts to the sweltering streets of Hyderabad, an intense heatwave has tightened its grip across Central and Peninsular India nearly two months ahead of the usual peak. 

For the millions stepping out each morning in Vijayawada, Hyderabad, or Punalur, the air feels different this year—thicker, heavier, and far more dangerous. And the science emerging alongside this heat offers little comfort. 

The Human Face of a Relentless Sun 

In Hyderabad, the capital of Telangana, the India Meteorological Department (IMD) recorded 38°C. But the real story lies in a number rarely discussed in daily weather bulletins: the Ultraviolet (UV) Index has touched 10. That reading, classified as “extremely dangerous,” means unprotected skin can burn in less than 15 minutes. Eye damage is a real risk. For outdoor workers—construction labourers, street vendors, auto-rickshaw drivers—the afternoon sun is no longer merely uncomfortable; it is a medical threat. 

“The UV index of 10 is not a summer routine,” says a public health researcher who tracks climate impacts in South India. “It signals a breakdown in the atmospheric filtering of solar radiation. When that happens alongside 40°C heat, the human body’s ability to cool itself through sweating becomes compromised far more quickly than standard temperature readings suggest.” 

Further north in Telangana, districts like Adilabad, Nizamabad, and Karimnagar are bracing for even harsher conditions, with forecasts predicting temperatures to exceed 40°C in the coming days. In neighbouring Andhra Pradesh, the Rayalaseema region—already known for its extreme summers—is expected to bear the brunt, while coastal cities like Vijayawada are not spared, with maximums touching 38°C. 

Kerala’s Unseasonable Scorcher 

Perhaps the most telling indicator of how profoundly the climate has shifted comes from Kerala—a state that has historically enjoyed more moderate temperatures due to its Western Ghats and coastal geography. On March 30, Punalur recorded a staggering 38.4°C, while Kottayam hit 37.8°C. These are not marginal increases. They represent a departure of nearly 3°C above the long-term average for this time of year. 

For a state still recovering from the devastating floods of recent years and the landslides that followed, this heat brings a different but equally insidious crisis. Soil moisture is evaporating faster. Water tables are under stress. And for the elderly and very young, the risk of heat exhaustion and heatstroke rises sharply with every degree above normal. 

The IMD has now issued heatwave warnings for Tamil Nadu as well, indicating that the band of extreme heat is expanding southward and eastward, engulfing regions that once served as summer refuges. 

A Warning from Across the Oceans: The US Southwest’s ‘Impossible’ March 

To understand just how abnormal this year’s pre-summer heat truly is, one need only look across the Pacific. The southwestern United States—Arizona, Nevada, inland California—has been hit by what meteorologists are calling an “extremely rare” March heatwave. Nearly 20 million Americans are under excessive heat warnings. Another 20 million face heat advisories. 

In Phoenix, Arizona, the temperature hit 40.5°C—the same as Rajnandgaon. But here is the crucial difference: Phoenix broke its March heat record by nearly 5°C. Las Vegas and parts of inland Los Angeles also saw record-shattering temperatures for this time of year. “These temperatures are completely off the scale for March,” said Ben Clarke, a co-author of a rapid analysis released by World Weather Attribution, an international consortium of climate researchers. 

The analysis delivered a sobering verdict: the climate crisis, driven primarily by the burning of fossil fuels, has made extreme heatwaves four times more likely to occur over the last decade. Even as recently as 2016, the same weather conditions would have produced a milder heatwave—about 0.8°C cooler. The co-author Friederike Otto put it in stark terms: “These findings leave no room for doubt. Climate change is pushing weather into extremes that would have been unthinkable in a preindustrial world.” 

The Oceans’ Fever: A Hidden Driver of Land Heatwaves 

While the sun blazes overhead, a less visible crisis is unfolding beneath the waves. A new joint study has established a direct causal link between rising ocean temperatures and the intensification of land-based heatwaves. According to the research, warming seas are driving between 50% and 64% of the increase in land heatwaves globally. 

The mechanism is both simple and terrifying. Oceans absorb more than 90% of the excess heat trapped by greenhouse gases. As sea surface temperatures rise, they alter atmospheric circulation patterns, pump more moisture into the air, and create conditions for humid heatwaves—the most dangerous kind. Humidity cripples the human body’s primary cooling mechanism: sweating. The study highlights the “wet bulb temperature” threshold of approximately 31.5°C as the physiological limit beyond which sweating becomes ineffective, and heatstroke becomes almost inevitable. 

The Indian Ocean, the study notes, is now a primary driver of widespread heatwaves across South Asia and West Asia. Similarly, record-breaking sea surface temperatures in the North Atlantic in 2023 led directly to widespread heatwaves in southern South America. The conclusion is inescapable: the same oceans that moderate our climate are now becoming engines of its most lethal extremes. The researchers suggest that rising sea surface temperatures could serve as early warning indicators for extreme heat events on land, giving communities perhaps days or weeks of advance notice. 

The Himalayas’ Vanishing Ice: A Slow-Motion Disaster 

While the plains of India swelter, the frozen heights of the Hindu Kush Himalayas are quietly disappearing at an accelerating rate. A new report by the International Centre for Integrated Mountain Development (ICIMOD) has found that the rate of glacier melt across this vast region has doubled since the year 2000. 

The report mapped 63,761 glaciers—the source of at least ten major Asian river systems, including the Ganges, Indus, Brahmaputra, and Mekong. These rivers support the food, water, energy, and livelihood security of billions of people. Approximately 78% of this glacier area, situated between 4,500 and 6,000 metres above sea level, is highly exposed to elevation-dependent warming—a phenomenon where temperatures rise faster at higher altitudes than at lower ones. 

The consequences are no longer theoretical. They have names and dates: the 2021 Chamoli disaster in the Garhwal Himalayas, where a dislodged glacieret likely killed over 200 people; the October 2023 glacial lake outburst flood (GLOF) at South Lhonak lake in Sikkim, which killed over 50; and the August 2024 Dharali disaster in Uttarakhand, where the glacially-fed Kheer Ganga swept away an entire market. Each event is a warning shot. As the glaciers thin and retreat, the glacial lakes they leave behind become unstable dams of debris and ice, waiting for a trigger. 

The Food Security Time Bomb 

If heatwaves, melting glaciers, and ocean warming were not enough, a new analysis by the International Institute for Environment and Development (IIED) adds a catastrophic dimension: global food systems are on a collision course with rising temperatures. 

According to the study, if the world heats up by 2°C—a threshold the current trajectory makes increasingly likely—the number of countries falling into critical food insecurity could almost triple, rising to 24 nations. The analysis projects that food systems in low-income countries will deteriorate seven times as fast as those in wealthy nations. 

The worst-affected countries would include Somalia, the Democratic Republic of the Congo, Afghanistan, Haiti, and Mozambique. Under a 2°C heating scenario, food insecurity is projected to increase by more than 30% in these nations. By contrast, high-income countries would see an average increase of just 3%. 

“Strengthening social protection systems that can respond quickly to climate shocks, investing in climate-resilient agriculture, and improving water and soil management” are the only ways to prevent this outcome, according to Ritu Bharadwaj, the study’s author. But these measures require political will, financial investment, and international cooperation—commodities that remain in frustratingly short supply. 

Living in the Unthinkable 

What ties these disparate stories together—the 40.5°C in Rajnandgaon, the UV index of 10 in Hyderabad, the melting glaciers of Sikkim, the record-shattering heat in Phoenix, and the looming food crisis in the Global South—is a single, undeniable truth. The unthinkable is no longer a future prediction. It is a March afternoon. 

For the people of Central and Peninsular India, the immediate challenge is survival. Health authorities must issue warnings not just about temperature but about UV exposure. Employers, particularly in construction and agriculture, need to adjust working hours. Cities need to map and publicize locations of cooling centres, ensure water availability, and check on the elderly and isolated. Schools must reconsider outdoor activities. 

But beyond adaptation lies the harder truth: every fraction of a degree of future warming is still negotiable. The rapid analysis from World Weather Attribution made clear that a 0.8°C cooler world—just a decade ago—would have produced milder heatwaves. Every tonne of carbon not burned, every hectare of forest not cleared, every policy that accelerates the transition away from fossil fuels, chips away at the worst-case scenarios. 

The heat is here. It is early. And it is telling us something that the glaciers, the oceans, and the food systems are screaming in unison: this is not a normal summer. And waiting for normal to return is no longer an option.