Belgium faces brief midweek warm spell and storms following sunny school return

Sunny start for the school return

Pupils across Belgium will return to classrooms on Monday under predominantly sunny conditions with scattered high-altitude cloud cover. According to forecasts issued by the Royal Meteorological Institute of Belgium, daytime temperatures will range from 18 to 21 degrees Celsius in the Ardennes and between 21 and 23 degrees Celsius across lower and central regions. Winds will blow moderately from the east to east-northeast throughout the day. By late afternoon, high cirrus clouds will begin pushing north from France, marking the approach of a broader atmospheric transition. During the night from Monday to Tuesday, cloud layers will thicken across southern districts, bringing isolated rain showers to areas south of the Sambre and Meuse rivers before dawn.

Midweek warmth and storm activity

The weather will turn increasingly unsettled on Tuesday as cloud bands and shower activity spread northwards across the country. Daytime maximum temperatures will settle between 18 and 25 degrees Celsius, accompanied by light to moderate easterly winds and isolated rumbles of thunder. A southerly airflow will establish itself by Wednesday, drawing warmer air over Belgian territory and lifting temperatures to between 20 and 26 degrees Celsius. Instability will intensify on Thursday as convective systems push out of France, generating locally heavy downpours and thunderstorms. Despite the unsettled conditions, Thursday will mark the warmest point of the week, with local maximum temperatures reaching between 23 and 28 degrees Celsius under south to south-easterly breezes.

Weekend rainfall and relief for dry terrain

A low-pressure system moving toward the British Isles and the North Sea will push a cooler maritime airmass into Belgium starting Friday. Daytime temperatures will drop to between 17 and 23 degrees Celsius, accompanied by sustained south-westerly winds, recurring showers, and occasional claps of thunder. The incoming precipitation will bring relief to regions affected by earlier summer drought conditions, which had heightened fire risks across the High Fens nature reserve. Royal Meteorological Institute meteorologist Pascal Mormal noted that cumulative rainfall across the country will be widespread.

In principle, we could have, by Sunday, accumulations locally reaching 40 to 50 litres per square metre. It is difficult to be very precise, but normally, everyone should receive their share of precipitation. It is rather good news.

Outlook for early September

Cool and changeable maritime weather will persist into early September, leaving little indication of a sustained late-summer heatwave over the coming week. Pascal Mormal indicated that temperatures at the start of next month may track near seasonal averages or drop one to two degrees below normal.

For the next ten days, there is no major signal of a lasting return of summer.

While seasonal models from French forecaster La Chaîne Météo point to warmer, anticyclonic conditions potentially developing during the second week of September across northern France, Belgian forecasters urge caution regarding longer-range projections. The immediate atmospheric pattern across Belgium will remain governed by variable Atlantic systems.