Sunset Cliffs Swell Statistics, March: All Swell – Any Wind
This chart illustrates the variation of swells directed at Sunset Cliffs through an average March and is based upon 2220 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the best grid node based on what we know about Sunset Cliffs. In this particular case the best grid node is 39 km away (24 miles).
The rose diagram describes the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but 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 39% of the time. Green and yellow represent increasing swell sizes and largest swells greater than >3m (>10ft) are shown in red. 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 biggest spokes, was WSW, 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 Sunset Cliffs and out to sea. We combine these with the no surf category of the bar chart. To simplify things we don't show these in the rose plot. Because wind determines whether or not waves are clean enough to surf at Sunset Cliffs, you can select a similar diagram that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. In a typical March, swells large enough to cause surfable waves at Sunset Cliffs run for about 61% 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.