Aramoana Spit Swell Statistics, December: Surf with Light or Offshore Winds
This image shows only the swells directed at Aramoana Spit that coincided with light winds or offshore conditions over a normal December and is based upon 2457 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 show increasing swell sizes and red illustrates highest swells greater than >3m (>10ft). In both graphs, the area of any colour is proportional to how frequently that size swell occurs.
The diagram suggests that the most common swell direction, shown by the longest spokes, was ENE, 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 6% of the time, equivalent to 2 days. Open sea swells exceeding >3m (>10ft) are unlikely to happen in a normal December but 5% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 5%, equivalent to (2 days). Taking into account the ratio of these swells that coincided with predicted offshore winds, and given the fact that Aramoana Spit is slightly protected from open water swells, we estimate that clean surf can be found at Aramoana Spit about 6% of the time and that surf is spoilt by onshore wind 13% of the time. This is means that we expect 6 days with waves in a typical December, of which 2 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.