Belgium Records Nearly 3,000 Heat Deaths This Summer

Nearly 3,000 people died as a result of three heatwaves that swept through Belgium this summer, according to final figures released by the country’s health institute, Sciensano. The institute recorded 2,935 excess deaths across the three heat periods between 18 June and 16 August — a 22.6 percent increase over expected mortality levels for the period.

The first heatwave, which ran from 18 June to 3 July, proved by far the deadliest, accounting for 2,035 excess deaths — an excess mortality rate of 48.8 percent. VRT NWS reported that this was the heaviest mortality during a heatwave since Sciensano began its analyses in 2000, both in absolute numbers and percentage terms.

A Summer of Records

The deadly toll came during what was officially the hottest summer ever recorded in Belgium since observations began in 1833. The Royal Meteorological Institute confirmed an average summer temperature of 20.3 degrees Celsius — the first time the seasonal average has exceeded 20 degrees — compared to a normal of 17.9 degrees, according to MeteoBelgie.

The summer was marked by four very warm periods separated by short cooler breaks that never truly brought relief. The first heatwave saw ten consecutive days of temperatures around 30 degrees Celsius, including three days near 35 degrees, with a peak of 35.5 degrees on 26 June. Nighttime temperatures remained exceptionally high, with ten nights above 18 degrees and two nights near 24 degrees.

The Deadliest Days

The peak of the crisis came on 27 June, when 641 deaths were recorded — an excess mortality rate of 146.5 percent. The following day saw 632 deaths, representing 143.1 percent excess mortality. Normally, approximately 260 deaths per day are expected in late June.

La Libre reported that the first heatwave’s exceptional mortality was driven by a combination of factors, including high ozone concentrations, atmospheric pollutant stagnation, and housing insufficiently adapted to extreme heat.

Regional Disparities

Regional differences were stark. During the first heatwave, Wallonia was hit hardest with 1,080 excess deaths — an excess mortality rate of 78.2 percent — followed by Flanders with 774 deaths (31.2 percent) and Brussels with 196 (65.6 percent).

The second heatwave, from 4 to 17 July, resulted in 535 excess deaths (14.8 percent), with 310 in Flanders and 198 in Wallonia. The third heatwave, from 28 July to 16 August, brought 365 additional deaths (7.0 percent), with 221 in Flanders and 171 in Wallonia. Brussels recorded no significant excess mortality during the final heatwave.

Heat Affects All Age Groups

While the elderly bore the brunt of the heat-related deaths, Sciensano’s data revealed significant excess mortality among people under 65 as well. During the first heatwave, 280 excess deaths were recorded in this age group — an excess mortality rate of 61.3 percent — demonstrating that extreme heat poses risks across all age groups.

Experts point to socio-economic factors to explain the regional disparities. Geert Molenberghs, biostatistician at UHasselt and KU Leuven, told RTL Info that “there is, for example, a big difference between Flanders and Wallonia. And there is an undeniable socio-economic factor there. In a large individual house surrounded by greenery, it is less hot than in a small overcrowded apartment.”

Walloon Minister of Welfare Yves Coppieters described his shock at the figures, telling La Libre he “fell off his chair” upon discovering the excess mortality numbers. He noted that social isolation was one of the most important risk factors during the June heatwave, and that life expectancy differences between some Walloon and Flemish municipalities can reach six years.

Highest Mortality in Europe

Belgium recorded the highest excess mortality in Europe during the June heatwave, according to data from the European Mortality Monitoring Network (EuroMOMO). The country’s excess mortality was higher than France’s (+23 percent) and the Netherlands’ (+13 percent), despite similar temperatures across the region.

The New York Times reported on Belgium’s situation as a case study into what went wrong, calling it “a warning for us all.” However, Sciensano cautions against direct cross-country comparisons, noting that different methodologies can affect results.

Understanding the Harvesting Effect

Some context for the mortality figures comes from the “harvesting effect” — the phenomenon where heat accelerates the deaths of people already near the end of their lives. VRT NWS reported that many of the excess deaths were among people aged 85 and older or those in palliative care.

“It is like with epidemics,” said Stefan Wynants, geriatrician at Jessa Hospital Hasselt. “First you get excess mortality that is then corrected again.” Research from the 1990s European heatwaves suggests that when deaths among people with less than 30 days to live are filtered out, the impact of a heatwave is roughly three-quarters smaller in terms of life-years lost.

Still, emergency doctors reported receiving many patients from overheated rooms in residential care centers, highlighting systemic vulnerabilities in Belgium’s healthcare infrastructure.

Political Response and the Road Ahead

Belgium’s existing heat plan was activated correctly and on time, but experts identified significant gaps: overloaded emergency call centers (112 and 1733), a lack of cool spaces, insufficient coordination between policy levels, and healthcare infrastructure not designed for extreme heat. An open letter from healthcare organizations described waiting times of ten minutes or more at emergency numbers during the deadliest weekend of the heatwave.

Federal Health Minister Frank Vandenbroucke acknowledged the shortcomings. “Today this is mainly a phase and communication plan,” he said of the current heat plan. “It still contains insufficient elements of a full preparedness plan with pre-developed measures, responsibilities, capacity planning and operational scripts for all sectors involved.”

A new comprehensive heat plan is expected to be ready by summer 2027, with initial principles to be presented at an interministerial conference in September 2026. The Risk Management Group has recommended that a real-time risk analysis be systematically conducted at the start of every alarm phase.

As VRT NWS’s political analysis noted, the next heatwave will be the real test of whether these measures can reduce the human toll. While heat deaths may never be eliminated entirely, the question remains whether Belgium’s response will match the scale of the threat posed by a warming climate.