Every summer, a familiar question surfaces across India, echoing from homes to newsrooms: is it genuinely hotter, or have we simply become more sensitive? This isn’t just some nostalgic lament or biological quirk. The evidence is clear and uncompromising: India’s heat is intensifying, creeping in earlier, stretching longer, and striking deeper than ever before.

What’s happening isn’t a trick of perception. It’s real. Heat waves, once occasional and brief, have become persistent forces reshaping daily life and work. According to the India Meteorological Department, a heat wave is declared when the temperature reaches at least 40° C in the plains or 30° C in the hills, with a deviation of 4.5° C or more above normal for at least two consecutive days.

These thresholds, once rare, are quickly becoming the standard during summer months. In states like Odisha and Rajasthan, what used to be brief seasonal heat spikes now stretch into longer, more frequent episodes, cumulatively spanning months. Between June 2010 and the summer of 2024, cumulative heat wave days soared from roughly 177 to 536 — a staggering increase of over 200%.

Heat wave days count the total number of days on which heat wave conditions are recorded across all affected regions. Since heat waves strike different places at different times, these days are summed nationally, so the total may surpass the length of the summer season in any single location.

Excess mortality analysis

Despite the increasing severity of heat waves, official data likely underrepresents their true impact. Various government departments collect and report heat-related deaths using different methods and sources, which can lead to variations in the numbers presented. Between 2000 and 2020, India recorded 20,615 heatstroke deaths, according to government records. However, many heat-related fatalities occur outside hospitals — at homes, construction sites or village farms, for example — where medical assistance and formal death certification may not always be accessible. As a result, deaths triggered by heat are often recorded under broader causes like cardiac arrest or respiratory failure.

The absence of standardised, mandatory heat-related death reporting and real-time surveillance means many such deaths remain uncounted, creating challenges for public health planning and response. Independent researchers and organisations have sought to address this gap using excess mortality analysis: comparing actual deaths during heatwave periods with long-term seasonal averages.

While some critics question the accuracy of these estimates and the methods used, excess mortality analysis remains a widely accepted and robust epidemiological tool. It captures both direct and indirect deaths related to heat, including those misclassified under other causes such as cardiac arrest or kidney failure, which are often missed in official counts.

For instance, the Global Burden of Disease study estimated approximately 155,937 heat-related deaths in India in 2021, encompassing fatalities from heat waves, prolonged exposure to high temperatures, and heat-aggravated conditions. Given the known underreporting in official data, such model-based estimates provide a more comprehensive and realistic picture of the true human toll of extreme heat.

Living with heat

The human toll of heat waves is paralleled by significant economic damage. The 2022 heatwave reduced wheat yields in key producing regions by approximately 4.5%, with some districts experiencing losses up to 15%. This disruption contributed to inflationary pressures on food commodities worldwide. Simultaneously, the heatwave triggered a power crisis as electricity demand surged to an all-time high of 207 GW, straining the grid and causing blackouts in some areas. Labour productivity in outdoor sectors such as construction and agriculture suffered dramatically, as workers faced an impossible choice between enduring hazardous heat exposure or forfeiting income.

According to the McKinsey Global Institute, heat-related productivity losses could jeopardise between 2.5% and 4.5% of India’s annual Gross Domestic Product by 2030, underscoring the urgent need for adaptive policies.

Ironically, India once knew how to live with heat. From the mud homes of Odisha to the sandstone courtyards of Rajasthan, generations designed spaces to cool without electricity. Rural routines followed solar rhythms: work began at sunrise, paused during peak heat, and resumed in the evening. Architecture used breathable materials like lime, thatch, and mud, keeping homes cooler than today’s concrete structures. In cities, water-cooled courtyards, shaded alleys, stepwells (baoli), and perforated stone screens (jaali) created microclimates. These systems weren’t folklore: they were practical responses to climatic conditions, embedded in culture and community.

A vivid example of this traditional wisdom is Navtapa, meaning “nine days of heat”. Observed from May 25 to June 2, it marks the sun’s entry into Rohini Nakshatra and was considered the most intense stretch of the summer. While rooted in astrology, Navtapa aligns closely with modern heat wave data. In this time, communities avoided heavy meals, rested during the midday, drank hydrating mixes like buttermilk and sattu, and provided shade and water for livestock. These practices, while culturally grounded, reflect sound physiological and environmental sense, and are today supported by modern science.

Why did these traditions wane? Not because they were ineffective but because modern development models evolved differently. Post-liberalisation planning favoured speed and scale, often overlooking climate sensitivity. Glass façades and concrete homes replaced breathable structures. Labour shifted from flexible agricultural cycles to more rigid, outdoor, informal urban jobs. Planning codes like the National Building Code don’t mandate passive cooling. Real-estate finance rarely supports traditional materials. Without institutional support or economic incentives, these practices couldn’t be sustained or scaled.

Invisible deaths

Meanwhile, India’s formal response to heat is gradually evolving. Notably, Ahmedabad’s heat action plan, implemented in 2014, has been associated with a significant reduction in heat-related mortality in the city, with an estimated 1,190 deaths avoided annually in its initial years.

Cities such as Bhubaneswar and Nagpur have initiated efforts to increase green cover and promote rooftop measures aimed at reducing heat absorption. However, many heat action plans remain largely advisory, often lacking binding mandates, dedicated budgets or clear accountability mechanisms.

Only a few cities have appointed trained climate officers or integrated heat considerations into their urban master plans. Public cooling shelters are limited in number, and awareness campaigns frequently rely on digital platforms that may not effectively reach regional language speakers, migrants, daily wage workers, and non-literate populations.

The rural landscape tells a tougher story. Despite most heat-vulnerable populations residing there, India still lacks a solid rural heat governance framework. Key programmes — including the Gram Panchayat Development Plans, the Mahatma Gandhi National Rural Employment Guarantee Act, and the National Health Mission — barely touch on heat issues. Unlike cities, villages have no counterpart to urban heat action plans. Panchayats often struggle with limited funding, staffing, and training, leaving them ill-equipped to set up cooling measures or modify work timings. Age-old water bodies, tree cover, and stepwells fade away, unsupported and overlooked. Many rural deaths remain invisible, depriving policymakers of crucial data.

Communicating heat risk

Beyond the bricks and mortar, a deeper gap persists: a disconnect between science and how people actually experience heat. Most don’t grasp the “feels like” temperature, which factors in humidity, solar radiation, and wind along with air temperature. So when the thermometer says 42° C, the body might be battling conditions closer to 50° C. That hidden burden, far beyond mere numbers, causes dehydration, heat exhaustion, and heatstroke. Public health messages rarely translate this into everyday terms, leaving too many unaware and vulnerable to the real dangers.

Equally important is how heat alerts are communicated. In many parts of India, advisories are issued in Hindi or English, shared via apps and social media that assume literacy, smartphone access, and digital fluency. This approach may exclude millions, especially the rural poor, migrants, and older citizens. Heat warnings should not be confined to digital platforms. They must be delivered through oral announcements, local radio, posters, community workers, and trusted institutions in regional languages.

Inclusive communication must reach every corner, every community. Otherwise, awareness remains partial and fragmented. India stands at a crossroads with a chance to harness the wisdom and experience already woven into its fabric. Immediately, districts — urban and rural alike — can start rolling out heat action plans tailored to their realities guided by the Disaster Management Act 2005. These won’t be abstract policies but grounded actions: pinpointing heat hotspots, setting up shaded rest spots, ensuring water access, and sending alerts that people trust and understand.

Looking beyond the immediate, national programmes like the Pradhan Mantri Awas Yojana, the Mahatma Gandhi National Rural Employment Guarantee Act, and the National Health Mission offer a canvas to embed climate sensitivity. Think reflective rooftops, more trees, natural ventilation: elements that cool homes and livelihoods alike. With financial channels like the Fifteenth Finance Commission and District Mineral Funds, local governments gain the muscle to scale these interventions fairly and effectively.

Down the line, real transformation demands more than isolated efforts. Building codes must evolve to favour passive cooling, urban and rural designs should be inclusive by default, and institutions must learn to speak the same language. Clear roles for the India Meteorological Department, National Disaster Management Authority, the State Disaster Management Authorities, municipal bodies, and village Panchayats are essential. Such coordination lets India shift from scrambling through heat emergencies to anticipating and managing them with resilience.

Knowledge isn’t the bottleneck. India’s heritage of traditional practices alongside modern science forms a rich foundation. The challenge lies in blending these, backed by political will and cohesive policy, to ready India for its hottest years ahead.

Ajay S. Nagpure is an urban systems scientist at the Urban Nexus Lab at Princeton University.