Airport Lefts Swell Statistics, December: Surf with Light or Offshore Winds
This image shows only the swells directed at Airport Lefts that coincided with light winds or offshore conditions through a typical December. It is based on 2457 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 largest swells greater than >3m (>10ft) are shown in red. In either graph, the area of any colour is proportional to how commonly that size swell happens.
The diagram implies that the prevailing swell direction, shown by the largest spokes, was SSW, whereas the the most common wind blows from the WSW. 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 44% of the time, equivalent to 13 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal December but 27% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 27%, equivalent to (8 days). Taking into account the proportion of these swells that coincided with expected offshore winds, and given the fact that Airport Lefts is exposed to open water swells, we think that that clean surf can be found at Airport Lefts about 44% of the time and that surf is blown out by onshore wind 56% of the time. This is means that we expect 30 days with waves in a typical December, of which 13 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.