Stinson Beach Swell Statistics, June: All Swell – Any Wind
The figure illustrates the range of swells directed at Stinson Beach over a normal June, based on 1834 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the optimum grid node based on what we know about Stinson Beach. In the case of Stinson Beach, the best grid node is 33 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 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 occurred only 74% of the time. Green and yellow illustrate increasing swell sizes and red illustrates largest 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 SW, whereas the the most common wind blows from the WNW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Stinson Beach and out to sea. We combine 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 clean enough to surf at Stinson Beach, you can view an alternative image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical June, swells large enough to cause surfable waves at Stinson Beach run for about 13% 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.