The flood was caused by the Vincinette low-pressure system,[4][clarification needed] better known as the Great Sheffield Gale, approaching the German Bight from the southern Polar Sea.

On Thursday 15 February, German authorities published the first storm warning for the North Sea with wind speeds up to 9 Beaufort.

The severe storm and the flood it caused in the last hours of 16 February affected the dykes more than predicted and led to some 50 breaches before officials raised the alarm for Hamburg.

Helmut Schmidt, then police senator of Hamburg, coordinated the rescue operations, and requested emergency help from countries throughout western Europe.

That meant overstepping his legal authority, ignoring the German constitution's prohibition on using the army for "internal affairs"—a clause excluding disasters was not added until 1968.