Heat Deaths in Wallonia Double Those in Flanders, Study Reveals

A devastating heatwave that struck Belgium between June 18 and July 1, 2026, has been confirmed as the deadliest on record since systematic monitoring began in 2000, with a stark regional disparity at its center: Wallonia recorded more than double the excess mortality rate of Flanders. According to data released by the Belgian health institute Sciensano, the heatwave caused 1,747 excess deaths nationwide — a 47.8% increase over the expected mortality baseline. Wallonia recorded 919 excess deaths (76% excess mortality), while Flanders recorded 682 (31.4%) and Brussels 159 (60.9%).

The Deadliest Heatwave in Three Decades

The 14-day heatwave brought 10 consecutive days near 30°C, three days reaching approximately 35°C (with a maximum of 35.5°C on June 26), and 10 tropical nights above 18°C — two of which approached 24°C, preventing the body from recovering overnight. The deadliest single day was June 27, with 641 deaths recorded — a 146.5% increase over the expected daily average of approximately 260. June 28 was nearly as severe with 632 deaths (+143.1%).

“It is the deadliest heatwave of the last 30 years,” said Toon Braeye, epidemiologist at Sciensano, as reported by VRT NWS. “Based on previous heatwaves, we had expected milder figures. But the type of heatwave we just experienced was unique, due to the succession of warm nights.”

This surpasses the previous record of 1,557 excess deaths during the August 2020 heatwave (+37.5%) and the August 2006 heatwave (+31%). More recent heatwaves had far lower impacts: 218 excess deaths in July 2022, 359 in August 2022, and 225 in June 2023.

Why Wallonia Was Hit Harder

The regional disparity has prompted urgent questions about the underlying causes. Researchers point to several interconnected factors. The heatwave’s epicenter was over France, resulting in higher ozone concentrations across southern Belgium. High ozone levels persisted for 10 consecutive days, with the European information threshold exceeded on June 25, 26, and 27. Elevated PM2.5 fine particle concentrations were also recorded.

Beyond meteorology, deep-seated socio-economic and health disparities between Belgium’s two main regions play a critical role. According to Gezond België / Statbel, life expectancy in Wallonia is approximately 2.8 years lower than in Flanders. Wallonia also has older housing stock with poorer insulation and energy efficiency, meaning homes retain more heat during extreme temperatures. Economic factors compound the vulnerability: historically higher unemployment rates and lower average incomes in Wallonia reduce residents’ capacity to adapt through measures such as air conditioning or home improvements.

All Age Groups Affected

Contrary to the assumption that extreme heat primarily affects the elderly, Sciensano recorded 280 excess deaths (+61.3%) among those aged 15-64. In residential care centers, 498 excess deaths were recorded. This demonstrates that the health consequences of extreme heat concern the entire population and underscores the importance of prevention measures regardless of age.

Policy Response and Calls for Action

Walloon Minister of Health Yves Coppieters (Les Engagés) described the figures as deeply concerning. “The figures must be taken with all necessary seriousness,” he said in a statement reported by La Libre. “They confirm that heatwaves now constitute a real public health challenge. They clearly exceed the impact of the August 2020 heatwave and reach, in some areas, levels comparable to those observed during certain episodes of the Covid crisis.”

On July 8, the Interministerial Conference (CIM) on Health proposed a series of new measures, including guaranteed access to cool spaces for vulnerable populations, strengthened outreach to isolated elderly individuals, improved access to drinking water, enhanced preparedness of institutions housing vulnerable populations, and reinforcement of the 1733 non-emergency medical number.

Broader Implications

The findings raise fundamental policy questions. Should heat action plans be region-specific rather than one-size-fits-all? Should housing renovation programs prioritize heat resilience alongside winter energy efficiency? How can working-age populations be better protected? And is the emergency response system — particularly the 1733 non-emergency medical number — adequately resourced for future extreme weather events?

Federal Health Minister Frank Vandenbroucke (Vooruit) has previously criticized the performance of the 1733 number, noting that during the thunderstorm weekend of June 27-28, no additional staffing was arranged at the emergency center. The CIM has now proposed reinforcing this system to reduce pressure on the 112 emergency number.

The disparity between Wallonia and Flanders demonstrates how climate change impacts are not evenly distributed within countries and how regional socio-economic inequalities can be amplified by extreme weather events. It challenges global assumptions that heatwave mortality is primarily an elderly issue and highlights the compound nature of climate risks, where extreme heat and air pollution combine to devastating effect.

What to Watch For

As Belgium faces the likelihood of more frequent and intense heatwaves due to climate change, the lessons from this record-breaking event are urgent. The Walloon government is expected to identify which of the proposed measures can be rapidly implemented within regional competencies, particularly regarding protection of isolated individuals, access to cool spaces, and improved access to drinking water. Longer-term questions around housing renovation, urban greening, and national climate adaptation strategy remain open — but the scale of this disaster has made them impossible to ignore. The combination of meteorological factors, baseline health vulnerabilities, housing quality, and economic disparities created a perfect storm in Wallonia, one that policymakers are now racing to address before the next heatwave arrives.