Tropical cyclones (also called hurricanes or typhoons) produce devastating wind and wave conditions that often result in significant loss of life and damage to coastal infrastructure. With ongoing climate change and sea level rise, the frequency and intensity of tropical cyclones occurring in the Atlantic, Pacific, and Indian Oceans are expected to increase. Storm surge flooding caused by tropical cyclones represents some of the deadliest and costliest natural disasters in the world. This chapter will explore the properties of tropical cyclones, as well as methods used to estimate their wind speed and the sea states they produce.