"Hurricane Iniki, for example, is ranked as the fifth-costliest catastrophe in U.S. history. Much of the damage was inflicted on the island of Kauai, Hawaii, in less than 1 hour. Hurricane Andrew ranks as the most costly in terms of insured losses. Damage comes not only from high winds, but also from the so-called marine overwash, a combination of effects resulting from tropical storm conditions that include storm surge, wind setup, wave setup, and wave swash. The primary effect is the storm surge resulting from extremely low atmospheric pressure. The vacuum created by the low pressure can raise mean sea level by several feet, a sort of upward bulge of the ocean wherever the tropical storm goes. Wind waves on top of the storm surge add to the effect, allowing sea water to run up and flood coastal areas by several tens of feet or more."
U.S. Geological Survey: http://www.usgs.gov/