Surf Forecast Surf Report
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Castle Island Surf Stats

All swells

(any wind direction)

Good Surf

(light / offshore wind)

This chart shows the combination of swells directed at Castle Island through an average March. It is based on 3460 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast wind or surf right at the coastline so we have chosen the most applicable grid node based on what we know about Castle Island. In the case of Castle Island, the best grid node is 24 km away (15 miles). The rose diagram describes the distribution of swell sizes and directions, 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 only 82% of the time. Green and yellow represent increasing swell sizes and red shows biggest 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 most common swell direction, shown by the biggest spokes, was SW, whereas the the prevailing wind blows from the W. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Castle Island and out to sea. We lump these in with the no surf category of the bar chart. To simplify things we don't show these in the rose diagram. Because wind determines whether or not waves are surfable at Castle Island, you can view an alternative image that shows only the swells that were expected to coincide with glassy or offshore wind conditions. In a typical March, swells large enough to cause good for surfing waves at Castle Island run for about 14% of the time.

Also see Castle Island wind stats

Compare Castle Island with another surf break

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