Although heat waves are the most significant extreme weather events in terms of mortality, their impacts are rarely considered from an economic perspective. This lack of awareness, coupled with a perception of risk that remains low, acts as a barrier to adaptation efforts. We present a monetary assessment of the health impacts of heat waves in mainland France between 2015 and 2020. Method - Health indicators tracked under the National Heat Wave Plan were used to estimate the costs of emergency room visits and SOS Médecins consultations for a selection of heat-related causes. Excess mortality and loss of life expectancy were also monetized, as was the loss of well-being due to activity restrictions. An approach based on the total cost of the disease (direct, indirect, and intangible costs) and willingness to pay was used. Results - Between 2015 and 2020, the health impacts studied amounted to a total of approximately €22 billion or €37 billion, depending on the method chosen. Excess mortality accounts for the majority of the cost (€16 billion when expressed in years of life lost, or €30 billion when expressed in terms of excess deaths), and activity restrictions are estimated at approximately €6 billion. Conclusions - This study provides a more objective assessment of the economic impact of these extreme weather events. In a context where climate trends point to rising temperatures and more frequent heat waves—which could exacerbate these impacts—these findings further underscore the importance and urgency of taking action to strengthen adaptation to heat waves.