The rose diagram illustrates the variation of swells directed at El Segundo Beach Jetty through an average northern hemisphere autumn, based on 5144 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the coastline so we have chosen the best grid node based on what we know about El Segundo Beach Jetty. In this particular case the best grid node is 46 km away (29 miles).
The rose diagram shows the distribution of swell sizes and swell direction, 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 9% of the time. Green and yellow show increasing swell sizes and red illustrates the largest swells, greater than >3m (>10ft). In either graph, 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 SW, whereas the the most common wind blows from the WNW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from El Segundo Beach Jetty and away from the coast. We group these 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 El Segundo Beach Jetty, you can view an alternative image that shows only the swells that were predicted to coincide with glassy or offshore wind conditions. In a typical northern hemisphere autumn, swells large enough to cause clean enough to surf waves at El Segundo Beach Jetty run for about 91% 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.