According to the National Center for Atmospheric Research, external winds can propel hurricanes across the ocean at sustained speeds of between 10 and 20 mph. Internally, hurricanes' wind speed is considerably higher.
Inside a hurricane, winds move much faster than the storm, as a whole, can move across open sea. The National Weather Service relates that hurricanes are divided among five categories according to the speed of their winds. Category 1 hurricanes have sustained winds of 75 to 95 mph, while winds in a Category 5 storm can rise as high as 157 mph. Anything over the 111 mph threshold for Category 3 is regarded as "severe."