Flanders Faces Rising Heat Risks: New Study Reveals Stark Inequalities Across Municipalities
Summers in Flanders are becoming dangerously hotter, but a new heat vulnerability map developed by the Flemish Institute for Technological Research (VITO) reveals that the impact is far from evenly distributed. The study, commissioned by the Flemish Department of Care, arrives in the wake of Belgium’s deadliest heatwave on record — a 12-day scorcher in June 2026 that caused approximately 2,000 excess deaths, according to the national health institute Sciensano.
A New Tool for Measuring Heat Vulnerability
The VITO heat vulnerability map assigns each neighborhood — down to the statistical sector level — a score from 0 to 10 based on a weighted combination of factors. These include heat exposure, population density, the share of children under 9 and adults over 65, socioeconomic status, the presence of vulnerable institutions such as hospitals and care homes, and the availability of green space. The higher the score, the greater the vulnerability, providing local governments with a granular tool to prioritize interventions.
As VRT NWS reported, the updated death toll of 2,000 excess deaths represents a 48% excess mortality rate — the highest since monitoring began in 2000. The deadliest single day was June 27, with 641 deaths recorded, a staggering 146.5% above normal.
Urban Heat Islands: Cities Bear the Brunt
The vulnerability map highlights a clear urban-rural divide. Cities including Antwerp, Ghent, Leuven, Mechelen, Vilvoorde, and Turnhout show the highest vulnerability scores, driven by the urban heat island effect. In Antwerp, scores range from 0 in the northern districts to 10 in the densely built city center. The municipality of Drogenbos in Flemish Brabant stands out as the most uniformly vulnerable area, with all its neighborhoods scoring 8 or higher.
VITO researcher Els Verachtert explained the nighttime danger: “In large cities like Brussels and Antwerp, it can be 3 to 5 degrees warmer at night than in the countryside. Our bodies can take quite a bit, but if the heat persists and you can’t cool down at night, you can’t recover.” She added that individual circumstances matter too: “If you live in a neighborhood with a high risk score, but you have a well-insulated house with air conditioning and a green garden, then there’s little to worry about personally. But for the local government, that score is the signal: we need to intervene here.”
A Heatwave That Broke Records — and Patterns
The June 2026 heatwave was exceptional not only in its intensity but also in its demographic reach. Unlike previous heatwaves that primarily affected the elderly, this one saw 61.3% excess mortality among people aged 15 to 64 — 280 excess deaths in that age group alone, according to the FPS Health Belgium. Regional disparities were stark: Wallonia suffered the highest toll with 77% excess mortality (1,059 deaths), followed by Brussels at 63% (188 deaths), and Flanders at 31% (768 deaths).
Three factors converged to make this heatwave so deadly: its duration (12 consecutive days), extreme daytime temperatures peaking at 35.5°C, and high ozone concentrations that exceeded 100 µg/m³ for 10 consecutive days.
Looking Ahead: A Fivefold Increase in Heat-Related Health Loss
The study’s projections for 2050 paint an alarming picture. Healthy life years lost to heat in Flanders are expected to rise from 2,500 to 13,000 per summer — a fivefold increase driven by three converging trends: climate change, a rapidly aging population, and urban densification policies that concentrate more people in city centers.
As Verachtert noted, “Greening alone is not enough. The effect of trees is quite local and cannot be applied everywhere.” The VITO researcher also cautioned that the model only accounts for premature mortality: “The thousands of people who end up in hospital due to heat or develop lasting health problems are not even counted here.”
What Comes Next
The heat vulnerability map is designed as a decision-support tool for local governments across Flanders. The Departement Zorg has made the interactive map publicly available, along with detailed handbooks and data sets, to help municipalities identify their most vulnerable neighborhoods and design targeted adaptation strategies.
A critical tension remains: despite local greening projects, Flanders is still “netto aan het verharden” — increasing its paved surfaces overall. As climate projections worsen and the population continues to age, the question is not whether Flemish communities need to adapt, but how quickly they can act — and whether the municipalities that need it most will get the support they require.