Under the interministerial directive on heat waves, the prevention of heat-related health effects relies primarily on local stakeholders, particularly municipalities. Santé publique France therefore sought to compile an overview of their practices regarding heat adaptation measures in urban areas and heat-related prevention for schoolchildren, the homeless, and vulnerable individuals (via municipal registries of elderly and disabled individuals who have voluntarily registered for alert and protection purposes). The objective was also to assess municipalities’ perceptions of risks and the challenges they face. Four online questionnaires were distributed in 2019 to all 34,839 municipalities in metropolitan France. Municipalities were contacted via an email sent to mayors and specific departments related to the questionnaire topics. Several hundred municipalities responded to all items in each questionnaire. Regarding registries of vulnerable individuals, the departments involved are often the Municipal Social Action Centers or dedicated municipal departments. Registration is based on criteria such as age (usually a minimum of 60 or 65 years old), disability, isolation, etc. During heat waves, registered individuals are contacted and, depending on the situation, receive advice, visits, assistance, or sometimes transportation to a cool location... Municipalities view these registries as enabling social and health monitoring, as well as the provision of advice or assistance, but they do not specifically target the most vulnerable and lack sufficient resources. In schools, some municipalities have implemented structural or situational improvements (planting greenery in the playground, insulation, shades, etc.), and a majority have procedures in place to inform about heat-related risks and ways to protect children (encouraging them to drink, keeping them in the shade, etc.). For the homeless, measures such as temporary summer housing or the provision of maps of water sources are rare, while support measures like outreach patrols are more common, in collaboration with associations or the Samu social. Finally, urban heat adaptation measures range from one-off summer initiatives (identifying and providing cool spaces, watering green spaces, misting systems, etc.) to urban planning measures (greening, heat-reflective paving, etc.). The results of this survey identify potential courses of action to improve protection of the population against heat waves at the municipal level. Thus, it would be appropriate to conduct an assessment and review of the relevance and effectiveness of municipal registries, evaluate the need to update or reorient them toward other systems, and improve the targeting and assistance of vulnerable individuals. It also appears important to better train and coordinate frontline workers who work with vulnerable individuals, schoolchildren, or the homeless. For the homeless, access to water and sanitation should be strengthened. In schools, efforts to improve heat-mitigation measures must continue. Finally, it is important to reduce urban heat, particularly through the concept of nature in the city, whose co-benefits extend beyond the context of heatwaves.