Santa Maria - Anjos Swell Statistics, Autumn: All Swell – Any Wind
This picture describes the variation of swells directed at Santa Maria - Anjos 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 optimum grid node based on what we know about Santa Maria - Anjos. In the case of Santa Maria - Anjos, the best grid node is 14 km away (9 miles).
The rose diagram shows 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 happened only 28% of the time. Green and yellow show increasing swell sizes and red represents the highest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how often that size swell was forecast.
The diagram indicates that the most common swell direction, shown by the largest spokes, was NW, whereas the the dominant wind blows from the WNW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Santa Maria - Anjos and offshore. We lump these in with the no surf category of the bar chart. To avoid confusion we don't show these in the rose plot. Because wind determines whether or not waves are good for surfing at Santa Maria - Anjos, you can select a similar diagram that shows only the swells that were predicted 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 Santa Maria - Anjos run for about 72% 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.