Belgium Could See First Heatwave of 2026 Next Week
Belgium may experience its first official heatwave of the year by the end of next week, with temperatures expected to climb back towards 30 degrees Celsius after a rainy weekend. Weather forecasters are closely monitoring the situation as a building high-pressure system from Southern Europe is set to push warm air northward.
Current Conditions and Transition
The weekend of June 13-14 is forecast to be rainy and cool, with temperatures between 14 and 21°C, serving as a transition period. According to Het Laatste Nieuws, the current cool and rainy period is caused by low-pressure systems over Scandinavia, but a significant change is on the horizon.
“From Monday we’re off to more summery weather,” said HLN chief meteorologist David Dehenauw.
Saturday will see rain gradually clearing from the west, with highs of 17-21°C. Sunday is expected to be the transition day, starting sunny but becoming cloudier, with temperatures between 14 and 20°C. The most likely scenario, according to Dehenauw, points to dry weather with frequent sunshine and highs between 17 and 22°C.
Jill Peeters, weatherwoman for HLN and VTM, welcomed the change. “It’s been since the Pentecost weekend that it was last summery. So it can come!” she said.
Temperature Forecast: Gradual Warm-Up
Temperatures are expected to rise steadily throughout the week:
- Monday, June 15: Sun and clouds, highs of 15-21°C
- Tuesday, June 16: Becoming warmer, highs of 20-25°C
- Wednesday, June 17: Sunny and warmer, highs of 22-28°C
- Thursday, June 18: Very warm, highs up to 29°C
- Friday, June 19: Potentially tropical, highs of 30°C or more
“Tuesday we can count on about 25 degrees. Wednesday the mercury rises further to 27 degrees and Thursday the weather even flirts with the 30-degree mark, with maxima up to 29 degrees,” Dehenauw told HLN.
Heatwave Potential
Frank Duboccage, weatherman for HLN and VTM, confirmed the possibility of the year’s first heatwave. “By Friday we will likely reach tropical temperatures of 30 degrees or more,” Duboccage said, as reported by Mancho.be. “The chance is there, but we naturally still have to wait a bit.”
According to the Royal Meteorological Institute (KMI), a national heatwave in Belgium is defined as at least five consecutive days with maximum temperatures of 25°C or higher, of which at least three days must reach 30°C or more, measured at the Ukkel (Uccle) weather station in Brussels.
Whether these criteria will be met remains uncertain. The stability of the incoming high-pressure system will be the determining factor, and thunderstorms could develop later in the week as warm, moist air creates atmospheric instability.
Climate Context: A Warm Spring
The potential heatwave follows what has already been an exceptionally warm spring in Belgium. According to VRT NWS, spring 2026 was the third warmest on record since measurements began in 1833, with an average temperature of 12.1°C compared to the normal of 10.5°C.
May 2026 was a month of extremes, ranging from -1.4°C on May 12 in Rossignol to 33.2°C on May 26 in Lier. The last ten days of May were the warmest ever recorded, and May became the 16th consecutive month with above-normal temperatures.
Belgium experienced two official heatwaves in 2025, and the frequency of such events has been increasing in recent years.
Broader European Heat Context
The potential Belgian heatwave would follow a pattern of extreme heat across Europe. May 2026 saw temperatures 10-15°C above normal across the continent, with London recording 35.1°C, France reaching 36°C, and Portugal hitting 40.3°C. Italy declared code red in four major cities as a heat dome over Western Europe drove temperatures to unprecedented levels.
Climate scientists link the increasing frequency of such heat domes to climate change and a weakening jet stream. The phenomenon occurs when a high-pressure system becomes blocked over a region for an extended period, trapping hot air beneath it.
Implications and Preparations
If the heatwave materializes, authorities may activate heat action plans, including cooling centers and health warnings for vulnerable populations such as the elderly, children, and those with chronic health conditions. Recent reports from the World Health Organization have highlighted over 200,000 heat-related deaths in Europe over the past four years, underscoring the seriousness of heat events.
Energy demand typically rises with temperatures as households and businesses increase cooling usage. Belgium’s rail infrastructure, vulnerable to heat-related track buckling, may see speed restrictions implemented. Agriculture could also face challenges, as a sudden heatwave following a wet spring may stress crops.
What to Watch For
Forecasters caution that long-range weather models can shift, and the exact timing and intensity of the temperature rise remain uncertain. The weekend of June 20-21 could bring thunderstorms as warm, moist air becomes unstable, potentially disrupting the heatwave pattern.
The KMI may issue official warnings as the event approaches, and local authorities across Belgium could activate their heat action plans. For now, Belgians are advised to stay tuned to weather updates as the situation develops.
After a rainy start to June and a spring that was already the third warmest on record, one thing appears clear: summer is finally on its way to Belgium. Whether it arrives with an official heatwave or simply a prolonged spell of warm, sunny weather, the coming week promises a significant shift towards summery conditions.