The rose diagram shows only the swells directed at Long Beach _5 that coincided with light winds or offshore conditions through a typical northern hemisphere autumn. It is based on 5144 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. Green and yellow represent increasing swell sizes and highest swells greater than >3m (>10ft) are shown in red. In both graphs, the area of any colour is proportional to how often that size swell was forecast.
The diagram indicates that the most common swell direction, shown by the largest spokes, was SSE, whereas the the dominant wind blows from the NNW. 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 13% of the time, equivalent to 12 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal northern hemisphere autumn but 3% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 3%, equivalent to (3 days). Taking into account the ratio of these swells that coincided with forecast offshore winds, and given the fact that Long Beach _5 is exposed to open water swells, we calculate that clean surf can be found at Long Beach _5 about 13% of the time and that surf is messed up by onshore wind 31% of the time. This is means that we expect 40 days with waves in a typical northern hemisphere autumn, of which 12 days should be surfable.
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.