Otago Peninsula - Allans Beach Swell Statistics, July: Surf with Light or Offshore Winds
The rose diagram shows only the swells directed at Otago Peninsula - Allans Beach that coincided with light winds or offshore conditions through a typical July. It is based on 2480 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 illustrate increasing swell sizes and red illustrates biggest swells greater than >3m (>10ft). In each graph, the area of any colour is proportional to how commonly that size swell was forecast.
The diagram implies that the dominant swell direction, shown by the longest spokes, was S, whereas the the prevailing 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 31% of the time, equivalent to 10 days. Open sea swells exceeding >3m (>10ft) are unlikely to occur in a normal July but 13% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 13%, equivalent to (4 days). Taking into account the ratio of these swells that coincided with predicted offshore winds, and given the fact that Otago Peninsula - Allans Beach is exposed to open water swells, we think that that clean surf can be found at Otago Peninsula - Allans Beach about 31% of the time and that surf is spoilt by onshore wind 37% of the time. This is means that we expect 21 days with waves in a typical July, of which 10 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.