Ocean Swell

Created in deep water waves head out towards the coast in a fairly predictable manner. This aspect of your forecast is normally dealt with well by the swell model but understanding the information here helps explain the local forecast and gives you a better understanding of why different countries and coasts experience different surfing conditions.


Within the storm waves of different size, power and shape are generated and the longer they are subject to the wind the more energy they contain. This is called windsea, it describes waves still subject to the winds that created them. In time most of the waves in a windsea will travel away from the winds that created them. Once this starts to occur they’re on their way to becoming ‘swell’. The tiny initial capillary waves created by the wind die quickly simply because of the surface tension of the water, but the larger waves are constrained only by gravity and, left unimpeded, can travel many thousands of miles from […]

How Storms Generate Swell

If you’ve read the articles on global weather you’ll have some idea how a storm is created, the next step is to understand how storms create swell. Anyone who’s watched high winds blow up chop on the surface of a lake or river will appreciate the first stage in this process and you might actually be more surprised to learn that the exact science of it is still only partially understood. Exactly how it happens really isn’t important to the surf forecaster, we just need to know that the wind initially blows up small chop called capillary waves. Once the surface has these bumps and dips the wind blowing over […]