Belgium’s public health institute Sciensano reported on Thursday that nearly 3,000 excess deaths were recorded during heat waves this summer, with revised figures showing the deadliest day alone accounted for 641 fatalities amid prolonged periods of extreme temperatures.

Regional mortality data

The second heat wave, which lasted from July 4 to 17, resulted in 535 additional deaths corresponding to an excess mortality rate of 14.8%, according to Sciensano data cited by French-language public broadcaster RTBF. Flanders recorded the highest toll at 310 deaths, followed by Wallonia with 198 and Brussels with 42. The third heat wave between July 28 and August 16 added another 365 fatalities, which the institute described as representing “slight” excess mortality.

Deadliest day and demographic impact

The single deadliest day of the summer remained June 27, when 641 deaths were recorded representing an excess mortality rate of 146.5%, according to the institute. Sciensano stressed that the impact of extreme heat extended beyond elderly populations, noting that “significant excess mortality was also observed among people under 65.” The public health authority attributed the elevated death toll to the duration of extreme heat episodes, rising temperatures and increased ozone pollution.

Summer heat context

Belgium experienced several periods of exceptionally high temperatures throughout the summer, prompting renewed concerns over the health effects of prolonged heat exposure. The institute released the revised mortality figures as authorities continue to assess the public health implications of increasingly frequent summer heat waves across the country.