The vast majority of the 15,000 deaths in the summer of 2003 can be attributed to a twofold lack of awareness: a lack of awareness of the danger posed by extreme heat, and a corresponding lack of awareness of how to protect oneself from it. This crisis has transformed our perspective on this issue. Drawing on their experience in the Provence-Alpes-Côte d'Azur region, the authors outline the steps to take in the event of extreme heat, emphasizing the protection of those particularly at risk: the elderly, infants, and people with chronic illnesses.