Belgium faced renewed 35°C heat as forecasters warned against calling it a confirmed heatwave

Updated 17 August 2026, 10:00 CEST — BRUSSELS. Forecasters warned on Monday, 10 August, that another surge of heat would push temperatures in parts of Belgium towards 35°C during the week, according to La Dernière Heure. The forecast raised the prospect of further records during an already punishing summer, but the Royal Meteorological Institute, or IRM, had not yet confirmed the episode as a climatological heatwave when the warning was published.

The distinction matters. The IRM defines a Belgian heatwave from measurements at its Uccle reference station: maximum temperatures must reach at least 25°C on five consecutive days, including at least three days of 30°C or more. A forecast of 35°C for one or more locations therefore signals dangerous heat, but does not by itself establish a nationwide heatwave or a “fifth major” episode.

The immediate concern was exposure rather than terminology. Under the IRM warning system, a forecast maximum of at least 35°C meets the threshold for an orange heat warning. The institute advises people to drink regularly, wear light clothing, remain in cooler rooms and monitor vulnerable relatives. Older people, young children, outdoor workers and people with heart or respiratory conditions face the greatest strain.

Belgium’s federal heat-and-ozone plan remains in its annual vigilance phase from 15 May to 30 September, according to the Federal Public Service Health. A warning phase begins when temperature criteria are exceeded, while the Risk Management Group can activate an alert when critical heat and ozone levels coincide. Regional authorities then apply their own action plans.

This summer had already exposed the pressure such episodes place on public services. On 8 July, Belgium’s public-health ministers said the federal plan had been activated correctly during the exceptional late-June heatwave and ordered stronger preparation for future events. The IRM said that early episode fitted a longer Belgian trend towards more frequent and extreme heat peaks.

For residents, the practical advice remains straightforward: avoid strenuous outdoor activity during the hottest hours, drink water before feeling thirsty, keep living spaces shaded and check on people who live alone. Confirmation of any heatwave, its duration and possible records depends on the IRM’s validated observations; those outcomes were not established by the original 10 August forecast.