As climate change contributes to more frequent and intense extreme heat events, residents of Detroit are increasingly vulnerable to heat-related illness. In summer 2012, the City of Detroit provided cooling centers for relief from the heat. This study proposes a spatial methodology to analyze various geographies for heat vulnerable populations using the City of Detroit as a sample case. This study creates a vulnerability index to identify those areas of Detroit that are most at risk, and then calculated the service area of each cooling center for pedestrians and bicyclists. We determined that 79% of Detroit’s most vulnerable population is within a 15 minute bike ride of a cooling center, but only 30% can reach a cooling center within a 15 minute walk. Therefore, we recommend that the city examine its current allocation of cooling centers and aim to strategically locate resources to improve the spatial coverage of this increasingly important service and improve the effectiveness of emergency response measures during future extreme heat events.