The graph illustrates the range of swells directed at Nova Almeida over a normal January and is based upon 1728 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the coastline so we have chosen the most applicable grid node based on what we know about Nova Almeida, and at Nova Almeida the best grid node is 22 km away (14 miles).
The rose diagram describes the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but without direction information. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These were forecast only 69% of the time. Green and yellow show increasing swell sizes and largest swells greater than >3m (>10ft) are shown in red. In either graph, the area of any colour is proportional to how commonly that size swell happens.
The diagram implies that the prevailing swell direction, shown by the largest spokes, was SSE, whereas the the most common 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 Nova Almeida 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 diagram. Because wind determines whether or not waves are good for surfing at Nova Almeida, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical January, swells large enough to cause clean enough to surf waves at Nova Almeida run for about 31% 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.