The rose diagram shows only the swells directed at Richardsons that coincided with light winds or offshore conditions over a normal September. It is based on 1680 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. Green and yellow represent increasing swell sizes and red shows the highest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how frequently that size swell happens.
The diagram suggests that the most common swell direction, shown by the longest spokes, was NE, whereas the the dominant wind blows from the E. The chart at the bottom shows the same thing but without direction information. For example, swells larger than 1.5 feet (0.5m) coincided with good wind conditions 11% of the time, equivalent to 3 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal September but 10% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 10%, equivalent to (3 days). Taking into account the ratio of these swells that coincided with expected offshore winds, and given the fact that Richardsons is exposed to open water swells, we estimate that clean surf can be found at Richardsons about 11% of the time and that surf is spoilt by onshore wind 62% of the time. This is means that we expect 22 days with waves in a typical September, of which 3 days should be clean enough to surf.
IMPORTANT: Beta version feature! Swell heights are open water values from NWW3. There is no attempt to model near-shore effects. Coastal wave heights will generally be less, especially if the break does not have unobstructed exposure to the open ocean.