San Mateo Surf Stats

The figure shows the variation of swells directed at San Mateo through an average June. It is based on 3266 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast wind and surf right at the shore so we have chosen the most applicable grid node based on what we know about San Mateo. In the case of San Mateo, the best grid node is 20 km away (12 miles). The rose diagram describes the distribution of swell sizes and swell direction, while the graph at the bottom shows the same thing but without 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 99% of the time. Green and yellow show increasing swell sizes and biggest 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 occurs. The diagram indicates that the prevailing swell direction, shown by the biggest spokes, was W, whereas the the prevailing wind blows from the SW. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from San Mateo and offshore. 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 surfable at San Mateo, 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 June, swells large enough to cause good for surfing waves at San Mateo run for about 1.0% of the time.

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