San Miguel - Areias Swell Statistics, Autumn: All Swell – Any Wind
The rose diagram illustrates the range of swells directed at San Miguel - Areias through a typical northern hemisphere autumn. It is based on 7252 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the shore so we have chosen the best grid node based on what we know about San Miguel - Areias. In this particular case the best grid node is 21 km away (13 miles).
The rose diagram describes the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing without direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These occurred only 27% of the time. Green and yellow show increasing swell sizes and red represents the largest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell occurs.
The diagram implies that the dominant swell direction, shown by the biggest spokes, was NNW, whereas the the most common wind blows from the W. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from San Miguel - Areias and out to sea. We lump these in with the no surf category of the bar chart. To simplify things we don't show these in the rose plot. Because wind determines whether or not waves are good for surfing at San Miguel - Areias, you can view an alternative image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average northern hemisphere autumn, swells large enough to cause clean enough to surf waves at San Miguel - Areias run for about 67% 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.