Observations and models reconstructing global temperature trends indicate an increase in the frequency, intensity, and duration of heat waves, particularly in Western Europe. Major cities are particularly vulnerable to heat waves due to their population density, land-use characteristics, urban heat islands, and the generation of anthropogenic heat and pollutants. This project, building on the authors’ previous work, combines satellite observations of temperatures in the Paris region during the August 2003 heat wave with a health survey on excess mortality among the elderly. The objectives of this study were (i) to better understand the spatiotemporal variation of surface temperatures in the Paris region based on land use and surface characteristics; (ii) to identify areas with critical temperature thresholds; (iii) to develop new thermal indices to define a more representative indicator of health risks; and (iiii) to establish a local satellite monitoring methodology for better risk anticipation and management. The method is based on the use of polar-orbiting satellites to obtain surface temperatures and interpret them. A series of 50 satellite thermal images (NOAA-AVHRR) and one multispectral image (SPOT-HRV) were used to analyze the spatial variation of diurnal surface temperatures during the heat wave (August 4–13). These images demonstrate (i) the contrast between the distribution of daytime and nighttime heat islands in relation to land cover and the thermal inertia of surfaces; (ii) the attenuation of heat by vegetation, (iii) the significance of high nighttime temperatures during the heat wave, (iv) the spatiotemporal variation of heat islands and areas with critical temperature thresholds, and (v) the correlation between the spatial distribution of the highest minimum temperatures and the highest mortality rates. Surface temperature at the addresses of 482 older adults (aged 65 and older, 281 deaths and 281 controls) was extracted from a series of 61 satellite thermal images (August 1–13). Indicators for minimum, maximum, and average temperatures, as well as temperature range, were constructed, taking into account the time interval between temperature exposure and health impact. The indicators were incorporated into a conditional logistic model, adjusted for various risk factors. The results indicate a significantly higher mortality risk for minimum temperatures over a 7-day period (day of death and the preceding 6 days) and over the total 13-day study period. They confirm the importance of nighttime temperatures and the duration of heat waves for health risks. The study demonstrates the value of remote sensing in understanding the intensity of heat waves in urban areas, as well as in anticipating and managing their health impacts. This study shows that it is possible to anticipate health risks not only in terms of probability, but also in terms of timing, location, and magnitude. These results should contribute to the development of strategies for adapting to and mitigating environmental and health vulnerabilities in the Paris region. The methodology can be applied to other metropolitan areas, taking into account available remote sensing instruments, geographic location, and local environmental and social parameters. (R.A.)