Stinson Beach Swell Statistics, June: All Swell – Any Wind
This chart describes the range of swells directed at Stinson Beach through a typical June and is based upon 2306 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind or surf right at the coast so we have chosen the optimum grid node based on what we know about Stinson Beach, and at Stinson Beach the best grid node is 33 km away (21 miles).
The rose diagram shows the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing without direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These occurred only 76% of the time. Green and yellow illustrate increasing swell sizes and red shows the highest 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 dominant swell direction, shown by the biggest spokes, was SW, whereas the the dominant wind blows from the W. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Stinson Beach and offshore. We lump these in with the no surf category of the bar chart. To keep it simple we don't show these in the rose diagram. Because wind determines whether or not waves are good for surfing at Stinson Beach, you can load a different image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average June, swells large enough to cause clean enough to surf waves at Stinson Beach run for about 11% 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.