This image shows only the swells directed at Manresa State Beach that coincided with light winds or offshore conditions over a normal October. It is based on 1736 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 red represents highest swells greater than >3m (>10ft). In either graph, the area of any colour is proportional to how frequently that size swell happens.

The diagram suggests that the prevailing swell direction, shown by the longest spokes, was WNW, whereas the the dominant wind blows from the NW. 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 47% of the time, equivalent to 15 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal October but 18% of the time we expect swell in the range 2-3m (6.5-10ft) 18%, equivalent to (6 days). Taking into account the ratio of these swells that coincided with forecast offshore winds, and given the fact that Manresa State Beach is exposed to open water swells, we estimate that clean surf can be found at Manresa State Beach about 47% of the time and that surf is messed up by onshore wind 47% of the time. This is means that we expect 29 days with waves in a typical October, of which 15 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.