India is growing rapidly, especially in its cities. Today, about 35% of the population lives in cities, and this is expected to go beyond 50% by 2050. To support this growth, the government is developing over 100 smart cities with better health, housing, education, and economic infrastructure. But this fast urban development is also causing problems, especially related to heat. Heat stress — when it gets too hot for the body to stay cool — is becoming a serious health risk and is a major cause of death, second only to lightning among weather-related deaths.

This study looks at how urban growth and land changes over 20 years have affected temperatures in more than 100 Indian cities. It uses satellite data and a special India Heat Index (IHI) to measure heat stress. Findings show that city areas have grown a lot, some by 400%, and temperatures at night are rising faster than during the day. Cities are more affected than rural areas. The study warns that growing cities will face more heat-related health risks and calls for urgent steps to manage heat stress and protect people, especially in urban areas.