Across India this summer, the old rhythm of heat has broken down. There was once a predictable pattern to the season: punishing afternoons followed by evenings that gradually softened, allowing homes, streets and bodies to recover. That cycle is increasingly failing. In many cities and towns, fans now seem to circulate hot air rather than relief. Water flowing through exposed rooftop tanks and metal pipes arrives hot even after midnight. Bedrooms remain stifling long after sunset. Sleep is interrupted, tempers fray, productivity declines, and health risks accumulate invisibly through the night.
This is the deeper story behind the India Meteorological Department’s repeated heatwave alerts across north, central and western India. Daytime temperatures crossing 40 degrees Celsius still make headlines, as they should. But the more consequential trend may be that nights are no longer cooling sufficiently. Minimum temperatures in several places have remained unusually high, while humidity in coastal and peninsular regions has intensified discomfort further. The difference between daily maximum and minimum temperatures has narrowed in many urban areas, creating round-the-clock heat stress rather than a temporary daytime spike.
The challenge before us is no longer merely summer heat. It is sustained heat exposure, amplified by urban design failures, social inequality, energy dependence and a warming climate. If the country does not respond promptly, each successive summer will become more punishing than the last.
Public discussion of heatwaves usually focuses on afternoon readings, dramatic sun exposure and images of places shimmering under a white sky. Yet hot nights are often more dangerous than hot days because they deprive the human body of recovery time. During the day, the body works to regulate internal temperature through sweating, increased circulation and reduced exertion. It relies on cooler night-time conditions to shed accumulated heat and restore equilibrium. When nights remain excessively warm, that recovery process weakens.
The consequences can be severe, especially for the elderly, infants, people with chronic illnesses and those living in poorly ventilated homes. Prolonged exposure to high night temperatures can worsen cardiovascular stress, aggravate respiratory problems, increase dehydration, disturb sleep cycles and heighten the risk of heat exhaustion or heat stroke. Sleep loss itself carries cascading effects on concentration, immunity, labour productivity and mental health.
This is particularly relevant in India, where millions of households do not have access to reliable cooling systems. Even where air-conditioners are present, high electricity costs or power interruptions limit their use. For those living in informal settlements, rented rooms with tin or asbestos roofing, or dense low-income neighbourhoods with little airflow, night-time heat can become inescapable. The body remains trapped in a thermal environment with no relief.
That is why the language of heat alerts must change. A warning based solely on daytime maximum temperature no longer captures the true scale of risk. Night temperatures, humidity levels and duration of heat exposure must become central indicators in public advisories.
India’s cities are now major contributors to their own heat burden. Concrete, asphalt, steel and glass absorb solar radiation through the day and release it slowly after sunset. Roads, parking lots, rooftops and commercial facades become giant heat reservoirs. Trees that once shaded streets have been cut back for road widening, real estate development or overhead infrastructure. Lakes, ponds and wetlands that moderated local temperatures have been filled or encroached upon. Dense construction blocks natural wind movement.
Waste heat from vehicles, diesel generators, factories and air-conditioners compounds the problem. Every poorly planned cooling solution can intensify ambient heat outside. This creates a vicious cycle in which those who can afford mechanical cooling escape indoors, while those who cannot are exposed to even hotter streets and lanes.
Even cities historically known for moderate climates are changing. Residents of Bengaluru, once proud of a weather system that made fans optional and air-conditioners unnecessary, increasingly report uncomfortable nights and hotter summers. Similar shifts are visible in hill towns, coastal belts and interior urban centres alike.
Urban planning in India still tends to treat heat as a seasonal inconvenience rather than a structural design issue. That mindset must end. Thermal comfort is now as fundamental to city planning as transport, drainage or water supply.
Heatwaves are not only environmental events; they are economic shocks. When temperatures soar, electricity demand rises sharply as households and businesses increase cooling use. Power grids face peak load stress. Water demand surges. Agricultural output can suffer through moisture stress, reduced yields or livestock distress. Outdoor labour productivity declines. Construction slows. Informal workers lose earnings when they cannot safely remain outdoors for long hours.
Food inflation often follows sustained heat. Vegetables wilt faster in transit. Milk production may fall when cattle face thermal stress. Poultry productivity declines. Cold-chain costs rise. If heat is followed by delayed or erratic rainfall, supply disruptions can intensify. Thus, a summer heatwave can ripple into household budgets months later.
Humidity adds another layer of danger. Human beings cool primarily through evaporation of sweat. When humidity is high, that process becomes less efficient. A moderately high temperature combined with oppressive humidity may be more dangerous than a higher but drier heat reading. Coastal India, riverine regions and parts of southern India are especially vulnerable to this compound stress.
For workers, this is already a labour crisis. Farmers, delivery riders, sanitation workers, street vendors, traffic police, factory hands and construction labourers are routinely exposed during peak heat hours. Many lack formal protections, insurance or medical support. As summers intensify, the absence of heat-sensitive labour regulation becomes harder to justify.
India’s labour codes, welfare systems and urban governance structures were designed for a cooler climate. They must now adapt to a hotter one.
India pioneered Heat Action Plans in several cities over the past decade. But the scale and character of today’s heat risks demand a second generation of planning. It must move beyond seasonal advisories and become integrated urban resilience frameworks. They should include neighbourhood-level heat mapping that identifies low tree cover, high-density housing, vulnerable populations and water-stressed zones. Public buildings can be designated as cooling shelters during severe events. Health systems need standardised protocols for recognising and treating heat illness, along with real-time reporting.
Building regulations should encourage passive cooling design rather than dependence on air-conditioning alone. Reflective roofs, shaded windows, ventilation corridors, insulated ceilings and heat-resilient materials can significantly reduce indoor temperatures. Programmes such as cool-roof schemes for low-income housing deserve expansion.
Water management must be central. In many homes, the sensation of hot tap water at night reflects rooftop storage systems directly exposed to the sun. Better tank insulation, shaded placement, leak reduction and decentralised rainwater harvesting can improve resilience.
Heat planning must also merge with monsoon preparedness. India now experiences extremes in clusters: intense heat, sudden storms, urban flooding and disease outbreaks in rapid succession. Cities that ignore drains during summer often pay for it during the first heavy rain.
No nation can sustainably air-condition its way through a climate emergency. If cooling demand alone becomes the dominant response, electricity systems will strain, emissions may rise where grids remain fossil-fuel dependent, and urban waste heat will worsen. India requires a broader climate compact that combines adaptation with mitigation.
That means rapidly expanding renewable energy while improving grid reliability, restoring urban lakes, wetlands and green corridors that cool cities naturally, prioritising public transport over car-centric growth that adds heat and pollution, investing in climate-resilient agriculture, drought management and crop diversification, and recognising thermal stress as a public health, housing and workers’ rights issue.
Most of all, it means placing equity at the centre of policy, because heat is not experienced equally: the wealthy can often purchase escape, the poor endure exposure, and the middle class absorbs rising utility bills. Children study in overheated classrooms, elderly people sit through sleepless nights, and women frequently bear the burden of fetching extra water, cooking in hot kitchens and caring for family members who fall ill.
When nights refuse to cool, the nation must understand what that signifies. It is not merely a rough summer. It is evidence that the old assumptions under which India built its cities, designed its homes and organised its economy no longer hold.
The monsoon may soon bring temporary relief, but relief is not a resolution. If the country waits for each summer to shock it anew, it will always be responding too late. India needs a long-term heat strategy now — before the next season arrives even harsher, and before the fan once again blows flames into another sleepless night.
Amal Chandra is an Indian author, policy analyst, and columnist. His debut book The Essential (2023) was launched by Dr. Shashi Tharoor and features a foreword by former External Affairs Minister Adv. Salman Khurshid. His research and commentary regularly appear in leading academic and popular publications. He posts on ‘X’ at @ens_socialis
Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth