The rose diagram describes the range of swells directed at Arguineguin through an average January, based on 1728 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind and surf right at the coast so we have chosen the most applicable grid node based on what we know about Arguineguin. In this particular case the best grid node is 43 km away (27 miles).
The rose diagram illustrates the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but lacks direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These were forecast only 96% of the time. Green and yellow show increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In either graph, the area of any colour is proportional to how frequently that size swell happens.
The diagram suggests that the most common swell direction, shown by the longest spokes, was SSW, whereas the the dominant wind blows from the NE. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Arguineguin and out to sea. We group these with the no surf category of the bar chart. To simplify things we don't show these in the rose graph. Because wind determines whether or not waves are clean enough to surf at Arguineguin, you can select a similar diagram that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical January, swells large enough to cause surfable waves at Arguineguin run for about 4% of the time.
IMPORTANT: Beta version feature! Swell heights are open water values from NWW3. There is no attempt to model near-shore effects. Coastal wave heights will generally be less, especially if the break does not have unobstructed exposure to the open ocean.