The rose diagram shows the combination of swells directed at Bunkers through an average November and is based upon 1680 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the shore so we have chosen the optimum grid node based on what we know about Bunkers. In this particular case the best grid node is 34 km away (21 miles).
The rose diagram illustrates the distribution of swell sizes and directions, while the graph at the bottom shows the same thing without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These were forecast only 33% of the time. Green and yellow show increasing swell sizes and red shows biggest swells greater than >3m (>10ft). In either graph, the area of any colour is proportional to how often that size swell occurs.
The diagram indicates that the most common swell direction, shown by the biggest spokes, was W, whereas the the prevailing wind blows from the SW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Bunkers and offshore. We lump these in 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 Bunkers, you can load a different image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical November, swells large enough to cause clean enough to surf waves at Bunkers 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.