India, July 6 -- Salespeople, daily wagers, a police patrol on a break, a couple of foreign tourists, and a waste picker - Delhi's largest "cooling zone" outside Jama Masjid metro station was packed to capacity. Some queued up for cold water while others huddled close to fans and coolers.

Squeezing in quietly, autorickshaw driver RK Shukla asked hesitantly if the air cooler could be adjusted: "It's the same problem at home. When it gets humid, my desert cooler throws warm air." This was late June when the pre-monsoon heat index-which measures how hot it feels-made Delhi suffocating. The highest it touched this month was 53deg Celsius.

The monsoon has reached northern India since, but rainfall alone does not guarantee thermal comfort. He...