Climate change doubled heat deaths in Belgium's June 2026 heat wave, study finds

A rapid attribution study by Vrije Universiteit Brussel indicates human-induced climate change made Belgium's June 17–28, 2026 heat wave 3.9°C warmer and more than doubled its death toll. Of 1,181 heat-linked deaths, 665 were directly attributable to anthropogenic warming. Record temperatures reached 35.5°C in Uccle, overwhelming 112 emergency services and hospital geriatric units. Vulnerability fell unequally on older populations, women, and deprived communities.

Attribution of Belgium's June 2026 heat wave deaths

• ▪A Vrije Universiteit Brussel study published in Zenodo combined epidemiological models and extreme event attribution methods to analyze mortality from the June 2026 Belgian heat wave.
• ▪Human-induced climate change made Belgium's June 17–28, 2026 heat wave 3.9°C hotter, causing 665 (56%) of 1,181 statistically linked deaths and more than doubling heat-related mortality during the period.

Record heat in Belgium during summer 2026

• ▪The summer of 2026 was the warmest ever recorded in Belgium and featured three officially declared heat waves.
• ▪The night of June 24–25, 2026 saw overnight minimum temperatures in Belgium stay at or above 24.1°C, the highest overnight minimum recorded during a Belgian heat wave since 1892.
• ▪Maximum temperatures in Uccle peaked at 35.5°C on June 26, 2026, during Belgium's deadliest heat wave on record.

Healthcare strain and mortality in Belgium

• ▪Provisional figures indicate June 27, 2026 was the second-deadliest day of the 21st century in Belgium.
• ▪Calls to Belgium's 112 emergency number reached nearly twice their normal daily volume on June 26, 2026, while geriatric wards reached full capacity.

Vulnerability factors in heat wave mortality

• ▪Vrije Universiteit Brussel researchers found that heat wave mortality risks disproportionately affect vulnerable groups due to compounding preexisting health conditions and socioeconomic disparities.
• ▪Vrije Universiteit Brussel researcher Emma Kuijt identified older people, women, and deprived communities with poorly insulated housing as bearing the highest risk during the June 2026 Belgian heat wave.

European impacts of the 2026 heat storm

• ▪The June and July 2026 heat storm set record June temperatures in Bordeaux, Budapest, and Bilbao, where heat reached 42.7°C.
• ▪European governments estimated that a June and July 2026 heat storm drove more than 10,000 excess deaths in Europe in a single week.

Global heat storm definition and trends

• ▪A Reuters analysis defines a heat storm as a heat wave covering at least 1% of the global surface at its peak.
• ▪The annual frequency of global heat storms increased from an average of about five per year in the 1960s to about 102 per year in the 2020s.
• ▪A continuous cascade of global heat storms has persisted for over 18 years straight since beginning on July 6, 2008.