Portland Surf Stats

This chart illustrates the combination of swells directed at Portland through an average April and is based upon 3360 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind and surf right at the shore so we have chosen the optimum grid node based on what we know about Portland. In the case of Portland, the best grid node is 22 km away (14 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 6% of the time. Green and yellow illustrate increasing swell sizes and red shows largest swells greater than >3m (>10ft). In either graph, the area of any colour is proportional to how frequently that size swell was forecast. The diagram suggests that the most common swell direction, shown by the biggest spokes, was SW (which was the same as the most common wind direction). Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Portland and away from the coast. We group these with the no surf category of the bar chart. To simplify things we don't show these in the rose graph. Because wind determines whether or not waves are surfable at Portland, you can load a different image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. In a typical April, swells large enough to cause good for surfing waves at Portland run for about 77% of the time.

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