Finally for a widely underestimated factor in determining the quality of the waves to surf on any given day, the swell period.
The swell period, or wave interval, is a measurement, in seconds, of the period of time it takes for 2 wave peaks to pass through 1 fixed point. The swell period is a vitally important factor to the quality of the waves on any one given day as, it measures the quality of the incoming waves.
The best quality waves are generated by ground swells hundreds of miles off the coast.
Applying this to wave quality is easy. Short swell periods of < 10 seconds usually indicate that the surf is local or regional and has been generated by local winds or regional currents. A low swell period correlates to low quality waves.
When you see a longer period of 13 seconds or more, as well as light offshore winds, the chances of pumping powerful surf is on!