San Miguel - Areias Swell Statistics, Summer: Surf with Light or Offshore Winds
This image shows only the swells directed at San Miguel - Areias that coincided with light winds or offshore conditions over a normal northern hemisphere summer and is based upon 7266 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 illustrate increasing swell sizes and red represents the largest 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 dominant swell direction, shown by the longest spokes, was NNW (which was the same as the most common wind direction). 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 8% of the time, equivalent to 7 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal northern hemisphere summer but 7% of the time you can expect swell in the range 1.3-2m (4-6.5ft) 7%, equivalent to (6 days). Taking into account the proportion of these swells that coincided with forecast offshore winds, and given the fact that San Miguel - Areias is slightly protected from open water swells, we calculate that clean surf can be found at San Miguel - Areias about 8% of the time and that surf is spoilt by onshore wind 30% of the time. This is means that we expect 35 days with waves in a typical northern hemisphere summer, of which 7 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.