Marshfield Jetty Surf Stats

This chart describes the variation of swells directed at Marshfield Jetty through a typical April, based on 3360 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the best 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 describes the distribution of swell sizes and directions, while the graph at the bottom shows the same thing but lacks 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 69% of the time. Green and yellow show increasing swell sizes and red illustrates the highest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell was forecast. The diagram implies that the dominant swell direction, shown by the biggest spokes, was NNE, whereas the the dominant wind blows from the WSW. 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 combine these with the no surf category of the bar chart. To avoid confusion we don't show these in the rose plot. Because wind determines whether or not waves are good for surfing at Marshfield Jetty, 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 April, swells large enough to cause clean enough to surf waves at Marshfield Jetty run for about 6% of the time.

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