From the processing of high- and low-resolution satellite images (Landsat and Modis), the development of bivariate correlations between daytime and nighttime land surface temperatures, and 27 metrics associated with urban structure and location, this work has analyzed the intensity of the phenomenon of Urban Heat Island manifested in Mexico City in one of the warmest months of the year 2018 to identify the most vulnerable areas to this phenomenon and their urban structure characteristics. Thus, the highest temperatures are found at a shorter distance from the inner city, as the most consolidated area. The population aged 65 or over, which is the most vulnerable to health problems associated with high temperatures and body thermoregulation, is located in areas of the city where the highest night temperatures are concentrated. Likewise, to a lesser extent, there is a direct correlation between high temperatures and areas with higher housing density, a greater surface area of paved streets, and a greater concentration of economic units per hectare. On the contrary, the zones with the lowest temperatures identified within the City were located in areas with the greatest heights above sea level, on steeper slopes, and with a greater surface of open areas. Likewise, the population aged 0 to 14 years, also identified within the range of vulnerability to high temperatures, is located mainly in areas with moderate and/or low temperatures. On the other hand, to identify the diurnal and nocturnal thermal variations, both in artificial and natural cover soil and their land use, thermal profiles were generated with measurements at every 1000 meters. This has allowed it to observe more pronounced thermal oscillations during the day, with the highest temperatures in the cultivation areas, residential land, and mixed-use. On the contrary, night temperatures stabilize and manifest the phenomenon of the Urban Heat Island in which it is shown that the highest temperatures are concentrated in the densest area of the city (Alcaldía Cuauhtémoc and Alcaldía Benito Juárez), which have stored a greater amount of heat due to the characteristics of the materials and composition of the urban environment, and the areas with a natural cover go down due to the ease of dissipating heat.