Thunderstorms are locally expected with: 10 to 30 l/m² in 1 hour, or 20 to 40 l/m² in 6 hours, or 25 to 50 l/m² in 24 hours, possibly with local strong windgusts or hailstones of 1 to 2 cm. Be careful.

Royal Meteorological Institute of Belgium

There is a risk of heavy thunderstorms with heavy rain (level 2 of 4). Max. gusts: < 60 km/h

Precipitation amounts: ~ 15 l/m²/1h

Hazard(s) caused by: lightning (danger to life!)

light objects flying through the air

isolated, rapid flooding of roads and subways

aquaplaning. Recommendations for what to do: Avoid staying outdoors and seek shelter (e.g. in buildings). Avoid being near lakes and rivers Secure loose objects. For example, fasten tents and coverings. Adapt your behaviour in road traffic. Avoid flooded areas and areas at risk (such as subways).

Deutscher Wetterdienst