Marshfield Jetty Surf Stats

This picture describes the range of swells directed at Marshfield Jetty through an average July. It is based on 3472 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the most applicable grid node based on what we know about Marshfield Jetty, and at Marshfield Jetty the best grid node is 15 km away (9 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 were forecast 92% of the time. Green and yellow illustrate increasing swell sizes and red represents the highest swells, greater than >3m (>10ft). In either graph, the area of any colour is proportional to how often that size swell happens. The diagram indicates that the dominant swell direction, shown by the largest spokes, was NE, whereas the the dominant wind blows from the SSW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Marshfield Jetty and away from the coast. 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 clean enough to surf at Marshfield Jetty, you can view an alternative image that shows only the swells that were forecast to coincide with glassy or offshore wind conditions. In a typical July, swells large enough to cause surfable waves at Marshfield Jetty run for about 0% of the time.

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