Belgium Braces for 35°C Heatwave and Severe Thunderstorms

Belgium is experiencing a tropical heatwave on Friday, June 19, with temperatures soaring up to 35°C across much of the country. The Royal Meteorological Institute (KMI) has issued a dual code orange warning — one for extreme heat and another for severe thunderstorms expected to strike from early evening. The coastal region is preparing for a bustling tropical weekend, while authorities warn that the evening storms could bring local damage.

Code Orange for Heat and Thunderstorms

The KMI has activated code orange for heat across ten provinces, including Oost-Vlaanderen, Antwerpen, Limburg, Vlaams-Brabant, Waals-Brabant, Brussels, Luik, Henegouwen, Namen, and Luxemburg. Only West-Vlaanderen remains under code yellow. Simultaneously, a separate code orange for thunderstorms covers West- and Oost-Vlaanderen, Antwerpen, Vlaams- and Waals-Brabant, Brussels, and Henegouwen, valid for Friday evening between 18:00 and 22:00, according to VRT NWS.

Meteorologist David Dehenauw of the KMI explained the severity of the forecast: “The weather computers are currently calculating the heaviest thunderstorms between 18:00 and 22:00 over the west and center, with locally heavy showers, hailstones, and very severe wind gusts. Local damage or disruption is likely.” He added that uncertainty remains, noting that “it is always a story of probabilities rather than certainties with thunderstorms.”

First Heatwave of the Year on Track

Thursday, June 18, was already the warmest day of the year so far, with 30.8°C recorded in Ukkel, surpassing the previous record of 30.5°C from May 29. According to Het Laatste Nieuws, the KMI forecasts that Belgium is on track for its first official heatwave of 2026. Under KMI criteria, a national heatwave requires five consecutive days with maximum temperatures of at least 25°C in Ukkel, with at least three days reaching 30°C or higher.

VRT weatherman Bram Verbruggen confirmed: “From Sunday we can officially speak of a heatwave in Belgium.” The heat is expected to persist through the weekend and into next week, with Monday and Tuesday potentially reaching 33-35°C again. Dehenauw noted that while the record 40°C from 2019 is unlikely, “it is not excluded that this heatwave will last a week.”

Coastal Preparations and Public Health Measures

The Belgian coast is preparing for a tropical top weekend, with hotels reporting an average occupancy rate of 90 percent, according to provincial tourism agency Westtoer. Multiple coastal municipalities have activated summer crowd management plans, including Oostende and Knokke-Heist. In every coastal municipality, at least one lifeguard post is operational. Wim Demeester, chairman of the coastal rescue service IKWV, urged beachgoers to swim only in supervised zones: “Just because you can swim in a pool does not mean you can swim in the sea. Go gradually into the water to avoid cold shock.”

The Interregional Environment Cell (IRCEL) has warned that ozone concentrations may locally exceed the European information threshold of 180 µg/m³. Sensitive individuals — including children, the elderly, and those with respiratory conditions — are advised to avoid strenuous outdoor activity between 12:00 and 22:00.

Energy Grid Strain and the ‘Hitzeflaute’ Phenomenon

A striking consequence of the heatwave emerged on Thursday evening when electricity prices surged from €11 per megawatt-hour to €550 per megawatt-hour. The sudden drop in solar generation — caused by clouds from approaching storms — combined with high air conditioning demand and unavailable wind power forced reliance on expensive gas-fired power plants. This phenomenon, dubbed “hitzeflaute” (heat lull), highlights vulnerabilities in Belgium’s energy grid as the country transitions toward renewable sources.

Broader European Context

The heatwave is not confined to Belgium. France is experiencing temperatures up to 40°C, with 26 departments under code orange. The French railway operator SNCF has cancelled 71 intercity trains due to the risk of air conditioning failure in older rolling stock. Paris has also allowed swimming in the Canal Saint-Martin for the first time as residents seek relief.

Looking Ahead

As the KMI forecasts continued heat through the weekend and into next week, multiple cities including Gent, Deinze, Tienen, and Mechelen have activated local heat plans, opening cooling centers and distributing water to vulnerable residents. Brussels Environment has announced that all parks and green spaces will close at 20:00 on Friday due to the storm risk.

The combination of extreme heat, severe thunderstorms, elevated ozone levels, and energy grid strain makes this a multi-faceted weather event. Residents are advised to stay hydrated, avoid strenuous activity during peak heat, and remain vigilant for thunderstorm warnings through the evening hours.