The aim of the Heat Index project is to develop an advanced algorithm capable of estimating a high-resolution heat index across Hong Kong. This effort is motivated by the unique thermal challenges of urban environments, where localized variations in heat perception can be substantial. Factors such as building shadows, terrain features, and urban morphology play a significant role in influencing how heat is experienced in different areas. For instance, shaded locations may feel significantly cooler than areas directly exposed to sunlight, while terrain obstructions and building density can alter wind flow, further impacting the perceived temperature.

The concept of perceived heat, or apparent temperature, goes beyond the actual measured temperature. It incorporates the combined effects of meteorological factors such as temperature, humidity, and wind speed, as well as environmental and physical conditions like altitude, building shadows, and exposure to direct sunlight. Building materials, urban density, and reflective surfaces in cities also amplify or mitigate heat conditions, creating micro-climates that standard temperature measurements cannot fully capture.