Discovery Bay Surf Stats

The rose diagram shows the variation of swells directed at Discovery Bay through a typical October, based on 2976 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 Discovery Bay, and at Discovery Bay the best grid node is 43 km away (27 miles). The rose diagram shows the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but lacks direction information. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. These occurred 70% of the time. Green and yellow represent 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 commonly that size swell occurs. The diagram implies that the dominant swell direction, shown by the longest spokes, was ENE, whereas the the prevailing wind blows from the E. Because the wave model grid is out to sea, sometimes a strong offshore wind blows largest waves away from Discovery Bay and offshore. We group these 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 clean enough to surf at Discovery Bay, 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 October, swells large enough to cause surfable waves at Discovery Bay run for about 30% of the time.

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