India's Urban Heat Crisis: Concrete, Asphalt and Lost Tree Cover Drive 'Heat Islands'

Sri Ganganagar in Rajasthan touched 48 degrees Celsius this week, the hottest reading in India so far in 2026. India Meteorological Department data show that since 1961, the frequency of heatwave spells over India's Core Heatwave Zone — central, northwestern and eastern coastal regions covering about 30 per cent of the country — has risen by 0.1 days per decade and the maximum duration by 0.55 days per decade. The World Meteorological Organization rates 2015 to 2025 as the warmest 11-year stretch since records began.

What makes Indian heat uniquely dangerous, however, is not the atmosphere alone. Urban heat islands across Indian cities now run between 2 and 10 degrees Celsius hotter than their surrounding rural areas. The gap is manufactured by concrete and asphalt, the loss of tree cover, and the waste heat exhaled by tens of thousands of air-conditioners cooling offices and homes. Delhi's average humidity rose by eight percentage points between 2015-19 and 2020-24, much of it traceable to increasingly sealed urban surfaces rather than global warming alone.

The Centre's response so far has been organised primarily through the National Action Plan on Heat-Related Illnesses, city-level Heat Action Plans coordinated by the NDMA and the India Cooling Action Plan (ICAP), 2019. Cities like Ahmedabad, where the first Heat Action Plan was launched in 2013, have demonstrated that targeted measures — early warnings, cooled public shelters, ASHA-level outreach, and water-distribution points — can sharply reduce excess mortality.

Sustained progress requires structural change. Building codes must mandate cool roofs, passive ventilation and green cover; urban planning must protect water bodies and wetlands; transport corridors must include shaded walkways; and labour laws should explicitly limit outdoor work during declared heatwaves. Informal-sector workers, who cannot stop working without losing income, must be brought under a heat-stress safety net. Without such measures, ever-hotter summers will continue to translate disposable national wealth into avoidable deaths.