Mere air temperature or land surface temperature, conveyed as minimum and maximum temperature twice a day, is no longer enough to combat heat during the harsh summer. The heat index, which layers temperature with other factors such as relative humidity, is a more accurate description of how hot it feels. Often called “feels like temperature,” it is usually several degrees higher than the air temperature. A 38 degrees Celsius reading can feel like 44-45 degrees Celsius in some places. The India Meteorological Department started communicating the heat index on an experimental basis this March and hopes to give India its own index, called the heat hazard score, next year. What is it? Why does India need one? Read on.