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Castlerock ratings
Quality on a good day: 3.0
Consistency of Surf: 4.0
Difficulty Level: 1.0
Crowds: 4.0

Overall: 3.3

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Surf Report Feed

Castlerock Swell Statistics, September: Surf with Light or Offshore Winds

This image shows only the swells directed at Castlerock that coincided with light winds or offshore conditions through a typical September and is based upon 2400 predictions, one every 3 hours. The direction of the spokes show where quality surf generating swell comes from. Five colours show increasing wave sizes. The smallest swells, less than 0.5m (1.5 feet), high are coloured blue. Green and yellow represent increasing swell sizes and red represents the biggest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell happens.

The diagram indicates that the prevailing swell direction, shown by the largest spokes, was WNW, 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 42% of the time, equivalent to 13 days. Open sea swells exceeding >3m (>10ft) are unlikely to arise in a normal September but 9% of the time we expect swell in the range 2-3m (6.5-10ft) 9%, equivalent to (3 days). Taking into account the proportion of these swells that coincided with forecast offshore winds, and given the fact that Castlerock is exposed to open water swells, we estimate that clean surf can be found at Castlerock about 42% of the time and that surf is messed up by onshore wind 47% of the time. This is means that we expect 27 days with waves in a typical September, of which 13 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.