Heat Stress Increases In Mega Cities Of India, Warmer Nights Add To Discomfort, Says Study. India's mega cities Delhi, Mumbai, Kolkata, Hyderabad, Bengaluru, Chennai are experiencing heat stress. According to Delhi based think tank Centre for Science and Environment, the cities are experiencing rising relative humidity over past two decades. The cities are also experiencing warmer nights turning the cities into 'urban heat islands'.  
