Deaths from all causes increased across hospitals, private homes and nursing homes during the heat wave.
The agency's analysis included people ages 15 and older, with mortality increasing beginning at age 45. Adults 75 and older accounted for roughly two-thirds of the provisional death toll, representing at least 3,719 excess deaths.
The Paris region was hit hardest, recording 1,999 excess deaths, more than 80% above what would have been expected without the heat wave, according to the agency.
Public Health France said 2026 recorded the country's highest excess mortality linked to a heat wave since 2003. The National Institute of Health and Medical Research estimated that roughly 15,000 more people died compared to the usual mortality for that time of year.
This year, the hottest days occurred on June 24 and June 25, when the national average temperature reached 86 degrees Fahrenheit. Peak temperatures also climbed above 104 degrees in many areas.
More than half of the excess deaths — about 56% — occurred during or immediately after the most intense stretch of the heat wave between June 25 and June 27.
Officials also said more than 10,000 excess deaths were reported across Europe during the peak of the heat wave, though the preliminary figures are expected to be updated in the coming weeks.
According to The Associated Press, funeral directors in Paris said they were inundated by the surge in bodies awaiting burial or cremation, with some mortuaries reaching capacity and turning down new arrivals.
Health officials noted that the excess mortality estimate includes deaths from all causes that occurred during the heat wave. The figures remain provisional and will continue to be refined in the coming weeks.
The Associated Press contributed to this report.