Physiological Equivalent Temperature (PET) has been widely used as an indicator for impacts of climate change on thermal comfort of humans. The effects of thermal stress are often examined using longitudinal observational studies over many years. A major problem in retrospective versus prospective studies is that it is not feasible to go back in time to measure historical data not collected in the past. These data must be reconstructed for the baseline period to enable comparative analysis of change and its human impact. This paper describes a systematic method for constructing a PET map using spatial analytical procedures. The procedures involve estimating PET values (based on the RayMan model and four key parameters of temperature, relative humidity, wind velocity, and mean radiant temperature) at a spatially disaggregated level comprising of a grid of 100 m × 100 m cells. The method can be applied to other geographic locations pending availability of basic meteorological and morphological data of the locations.