The Heat Wave and Health Alert System (SACS) was established in early summer 2004. It uses forecasts of meteorological indicators to issue heat wave alerts that trigger a response defined under the National Heat Wave Plan (PNC). A syndromic surveillance system allows for monitoring the potential health impact of a heat wave on a day-after basis. Over the years, SACS has been evaluated both internally and externally and has undergone logistical and scientific improvements. This report presents the principles of SACS, the main stages of its development and evaluation, and reviews the meteorological and health indicators monitored from 2004 to 2011. The system’s limitations and prospects are discussed, particularly its potential for adaptation in the context of climate change, demographic shifts, and changes in healthcare and public health practices, as well as changes in people’s behaviors since the August 2003 heat wave and the subsequent implementation of the PNC. (R.A.)