Urban Warming is an increasing problem in the cities, and inadvertently Thermal Comfort has received an increased attention since the last decade. Compared to indoors, the outdoor environment is more complex and there are larger variations in the climatic parameters. The present research is an effort towards evolving “Human ‘Outdoor’ Thermal Comfort Index”, so as to overcome the limitations of prevalent indices such as ‘Physiological Equivalent Temperature’ and ‘Universal Thermal Climate Index’. The present study was carried out at twenty Public Green Spaces, selected on the basis of geographical location, land use pattern, public prominence, topography and physical area; for 12 hours to monitor Climatic Parameters. The Input parameters included Ambient Air Temperature, Relative Humidity, Wind Speed, Intensity of Sunlight, Green-cover Area; and Public Perception which was ascertained at each observatory with the help of a self-designed compact questionnaire survey. Subsequently, this newly designed empirical relationship was employed for establishing the Thermal Comfort Index of various Public Green Spaces of Bengaluru, with ranking.