Storm tides of the North Sea are coastal floods associated with extratropical cyclones crossing over the North Sea, the severity of which are affected by the shallowness of the sea and the orientation of the shoreline relative to the storm's path, as well as the timing of tides. The water level can rise to more than 5 metres (17 ft) above the normal tide as a result of storm tides.
Northern Germany and Denmark are particularly susceptible to storm tides. The coastline of the German Bight forms an L-shape facing northwest. Also vulnerable are the United Kingdom and the Netherlands, where the sea shallows and is funnelled toward the English Channel.
Storm tides are a regular occurrence in the North Sea basin; several form each year. Although most do not cause significant damage, the impact of some has been devastating. During one, the February flood of 1825, the Danish coastline changed, as the North Jutlandic Island became separated from the Jutland Peninsula.