Back Beach Swell Statistics, Luglio: Surf with Light or Offshore Winds

This image shows only the swells directed at Back Beach that coincided with light winds or offshore conditions over a normal July. It is based on 2976 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours represent increasing wave sizes. Very small swells of less than 0.5m (1.5 feet) high are shown in blue. Green and yellow represent increasing swell sizes and red shows biggest 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 WSW, whereas the the prevailing wind blows from the SW. 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 19% of the time, equivalent to 6 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal July but 6% of the time we expect swell in the range 2-3m (6.5-10ft) 6%, equivalent to (2 days). Taking into account the fraction of these swells that coincided with expected offshore winds, and given the fact that Back Beach is slightly protected from open water swells, we estimate that clean surf can be found at Back Beach about 19% of the time and that surf is messed up by onshore wind 51% of the time. This is means that we expect 22 days with waves in a typical July, of which 6 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.