The rose diagram shows the variation of swells directed at Campus Point over a normal northern hemisphere spring. It is based on 4842 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 best grid node based on what we know about Campus Point, and at Campus Point the best grid node is 47 km away (29 miles).
The rose diagram shows the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing but lacks 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 20% of the time. Green and yellow illustrate increasing swell sizes and red represents the biggest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell occurs.
The diagram indicates that the prevailing swell direction, shown by the longest spokes, was W, whereas the the prevailing wind blows from the WNW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Campus Point and away from the coast. We combine 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 surfable at Campus Point, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical northern hemisphere spring, swells large enough to cause good for surfing waves at Campus Point run for about 58% 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.