Heat related death is currently the number one weather-related killer in the United States.Mortality from these events is expected to increase as a function of climate change. The proposed activity seeks to augment the current Heat Watch/Warning System (HWWS) with NASA instruments and models used in conjunction with socioeconomic and heat-related mortality data. This activity will enable the production of a more spatially specific warning for areas of risk within the cities, a current limitation of the HWWS. We plan to use the MODerate resolution Imaging Spectroradiometer (MODIS), Landsat Enhanced Thematic Mapper (ETM+), Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), and once available the Visible/Infrared Imager/Radiometer (VIIRS) system to model surface temperatures during extreme heat events in three U.S. cities. Modeling the thermal properties of each city, incorporating established socioeconomic factors of risk, and heat-related mortality data will enable us to reach this realization. The modeling approach will use logistic regression as well as artificial neural networks to enable us to fine tune a risk model and make it spatially and temporally extensib le. We see the models developed as able to be implemented in other U.S. cities once the project is completed. The primary end users of this system will be the health departments of each city. These departments are primarily responsible for intervention during heat alerts. The evaluation of this proposed system will use phone surveys before and after implementation to determine effectiveness of the extension. We will additionally measure a baseline of performance of the current HWWS in each city and evaluate against this near the time of project completion. We anticipate developing a model of vulnerability, which will lead to a reduction of mortality during such extreme heat events, thus providing a direct societal need using NASA data and other geospatial assets.