Waves’ speed, or period, is measured by clocking how fast a complete wave crosses a designated point.
Fast wave periods result from strong, long-blowing winds. Out in the ocean, wave periods range from less than one tenth of a second to more than 24 hours.
Depending on their speed, most waves are classified as gravity waves (greater than one tenth of a second and less than 5 minutes) or long waves (more than 5 minutes, but less than 12 hours).
Along the coastline, most wind-generated waves have periods between 5 and 20 seconds.