Currently cities and climate are coevolving in a manner that could place more vulnerable populations at risk from exposure to excessive heat. The magnitude of recent heat waves and their impacts in many urban areas in the U.S. and Europe indicate an urgent need for increased awareness to the heat wave phenomena and understanding the underlying vulnerabilities. As a complimentary effort to the development of the EPA/NOAA/CDC/FEMA Excessive Heat Events Guidebook, within the realm of the Weather and Society: Integrated Studies program, this study focused on a spatial analysis of vulnerability and risk to excessive heat in two urban areas in the U.S.: Phoenix and Philadelphia. Two cities were analyzed in terms of their climatology, environmental and societal characteristics, previous cases of excessive heat impacts, and existing strategies for heat-wave mitigation. Geographic Information Systems (GIS) and spatial statistics were used to identify spatial patterns of biophysical and social factors contributing to the heat-related morbidity and mortality. Combination of social and physical factors allowed for identification of “hot spots” or areas of potential risk from excessive heat that were strongly related with recorded heat-wave mortality. Considering the potential interactions of multiple risk factors produces a more complex understanding of vulnerable populations that may inform mitigation strategies. This kind of spatial analysis, when enhanced with mesoscale forecast (model) data, could be used operationally to inform targeted impacts intervention.