Surf Forecast Surf Report
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Birsay Bay Surf Stats

All swells

(any wind direction)

Good Surf

(light / offshore wind)

This picture illustrates the combination of swells directed at Birsay Bay through a typical March, based on 3460 NWW3 model predictions since 2007 (values every 3 hours). The wave model does not forecast surf and wind right at the shore so we have chosen the optimum grid node based on what we know about Birsay Bay. In the case of Birsay Bay, the best grid node is 17 km away (11 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 represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. These happened only 17% of the time. Green and yellow illustrate increasing swell sizes and red illustrates the largest swells, greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how commonly that size swell happens. The diagram implies that the dominant swell direction, shown by the biggest spokes, was WNW, whereas the the most common wind blows from the SW. Because the wave model grid is away from the coast, sometimes a strong offshore wind blows largest waves away from Birsay Bay and out to sea. We combine 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 surfable at Birsay Bay, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. Over an average March, swells large enough to cause good for surfing waves at Birsay Bay run for about 83% of the time.

Also see Birsay Bay wind stats

Compare Birsay Bay with another surf break

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