Urban development is often accompanied by anthropogenic activities, changes in land morphology and serious damage to natural areas. Consequently, the urban climate is also affected, as temperatures are higher in urban centers and because of the presence of the urban heat island phenomenon, which poses a health threat to local citizens. The Monterrey Metropolitan Area (MMA) is the second-largest urban area in Mexico and is characterized for rapid urbanization and industrialization processes, steep climate conditions and the presence of urban heat islands. This combination makes living conditions rough for its inhabitants, especially for vulnerable groups. In order to quantify and compare heat vulnerability in urban areas, metrics such as the Heat Index measure the heat exposure and its effects on the human body. This study interpolated both relative humidity and temperature information from 15 local climate monitoring stations to determine the Heat Index for the six hottest weeks of the 2023 summer in the Monterrey Metropolitan Area. The interpolation methodologies used (IDW, Kriging and Spline) were later compared in order to cross-validate the results and define the most accurate performance based on both MAE and RMSE statistical analysis.