Wind which blows over the water exerts a shear stress. The surface water particles move in the wind direction. This results in a surface current. If a storm generates a current from the same direction over a long time, the current will cause large water elevations when it reaches the coast. The effects of wind shear may also combine with low atmospheric pressure. The result is a storm surge.

The height of the storm surge depends on the wind force and direction, the fetch (i.e. the length over which the storm generates the currents), the atmospheric pressure, the water depth and the coastal profile. The storm surge of February 1953 in the Netherlands, causing severe damage and loss of lives, was about 3 m above the predicted astronomical high water level (see Fig. 48).

The effect of a storm surge on a dune coast is a significant change in profile, characterized by severe erosion of the dune toe (see Fig. 49). Consequently, the coast recedes over a distance r (see Fig. 50). Yet, the coast will be restored during the following calmer seasons provided that it is stable (seen over a long period). In order to avoid damage to buildings, a distance R at the coast must be preserved for reversible erosion. A probability study can reveal the preservation distance (=R) which will only be exceeded with a chosen frequency (see Fig. 50).