Swell is how we describe waves generated by storms far offshore. Thus, there can be a large swell even during locally calm conditions. In my experience, swell is usually 3′ or greater. Swell over 24′ is pretty extreme. Any time swell is over 12′ the surf gets pretty rough.
The graph above shows a frequency distribution of swell heights I have experienced while exploring the outer shores over the last three years. This information is biased toward low values because I’m rarely out on the beach during rough conditions. I guess what you see here is a depiction of my preferences for gentle surf.
Usually the waves roll up the beach straight out of the west, the result of a west swell. Sometimes waves are generated from other swells. I recorded the swell direction for several trips to the outer shores and the graph above shows the frequency of the the different swells I encountered. In a boat or on the beach, things get kind of crazy with a mixed swell. I thought there might be some relationship between swell direction and the size of the seas so I plotted what I found in the graph below. There wasn’t much of a relationship, but the sample is small for most swell directions.
In this graph the number above each swell direction is the number of observations and the vertical lines are the standard deviation.
theoutershores 