Graphs of swell size and period from the wave buoys around Cornwall for the last 24 hrs can be seen here, and a quick summary on the front page. Below you'll find a quick description of the information they provide.

Swell/Wave Height

The reported swell height is the mean averaged swell height for the last 1 hour period, the wave which hits the shore is generally a half to a third of the the height of the reported swell when the swell period is below 9 seconds, above 10 seconds, especially if the wind is light, the wave height at the shore can be 80-100% of the swell height, which is when you know you're onto a winner!

Swell/Wave Period

The reported swell period (time taken for successive wave peaks to pass a given point) is given in seconds, the longer the period the more powerful the swell and the further it has traveled across the atlantic. Wave height and period tend to rise and fall together. For Cornwall ground swells (which are good) start with a period of about 8-9 seconds.

Predicted Wind

The predicted wind forecast provides an average or trend wind direction for the whole of cornwall, as such use it as a rule of thumb, and not an absolute measure of the wind direction at every beach (Cornwall's a big county), use local knowledge as ever to interpret how local headlands and bays will bend the wind. The information is updated hourly.

Wind Direction

Wind direction is reported as one of the cardinal points of the compass, rather than the direction in degrees of the compass the wind is coming from. Again the wind direction is the average for the previous 1 hour period. For surfing the wind should ideally be directly offshore at the place you plan to surf.

Wind Force

Rather than expressed in miles an hour this is given as wind force on the Beaufort scale, which ranges from 0 for calm to 12 for a hurricane. You want wind force/speed low in value, as strong off shore winds will flatten swells and make them harder to catch, as well as blowing you back up the wave. Obviously an onshore wind unless very light is bad as it pushes the wave over. Find below a full description of the Beaufort scale. NOTE: in the following table wave height is expressed for open ocean and not the shore line where the wave will be smaller.

Updated Time

New wave data becomes available for each of the wave buoys about once an hour, although we check for updates every 15mins, note the time of retrieval is recorded in GMT (or UTC) so in British Summer Time (BST) remember to add an hour otherwise it will appear the readings are older than they are. That said they generally lag behind current time by an hour.

Accuracy

As you will notice every now and again either data is missing, in which case it is marked with a "--" or it simply becomes over two hours old, this is unfortunately a feature of the wave buoy feeds and there is nothing I can do about this, check the graphs and you should soon be able to identify the bad data and still see the wave trends.