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Swell forecasting – the basics

Posted by The Surfboard Warehouse on

Basically, there are 2 things that influence surf conditions, the wind and the swell. If you’re well informed about both these things, you’ll have a better understanding of what the waves are doing at your favourite surf spot.

swell, surfing, surfboard, forecast, waves

Surf reports are a great way to get a quick update on the surf, but reading swell charts is the best way to stay updated on the conditions now and into the future. But it can get complicated. We’ve broken it down for you and given you some basic information to get started.

When navigating swell charts there are 4 things you need to look at, wind, swell direction, swell height and swell period.

The wind

The wind can be difficult to predict, it can be fickle and change in a matter of hours. It’s important to know what wind is offshore and onshore at the location you want to surf. Offshore winds are optimal, producing clean, glassy conditions. Onshore winds make the surf choppy and messy, but if they’re only light, the surf can still be fun.

You need to check the wind direction as well as the wind speed. It also pays to check the entire day’s forecast, as wind can change from morning to afternoon, depending on the location. Some spots only work in a certain type of wind and other more protected breaks perform well even if the wind's howling onshore everywhere else.

The swell direction

The swell direction is obviously the direction that the waves are coming from. Every surf spot performs better when the swell is coming from a certain direction. For instance, Snapper Rocks on the Gold Coast is great in an east/south-east swell, however a larger south swell can produce perfect waves running all the way down the point if it's large enough to wrap into the protected sand bottom point break.

If you’ve ever looked out at the horizon and seen a heap of swell, but none hitting the shore, it's because the swell is passing by and is not heading in the right direction for your location.

swell, surf, waves, surfing, forecast, surfboard An example of a swell chart, the arrows showing the swell direction. Image via magicseaweed.com

The swell size

Depending on the size of the swell, it could be the difference between taking out your fish shaped board or your 6’10”gun. The size of the swell is measured off the average set wave and is a major factor in determining the size of the waves when they hit land.

All swell forecasting websites tell you the size of the swell and will predict the most dominant swell over the next seven days.

It all sounds pretty simple, larger swell means bigger waves, but other factors come into play such as the swell period.

The swell period

The swell period is very important. It is calculated by measuring the time successive waves pass the exact same point, normally measured by a buoy off the coast.

If the periods are long, when the waves hit the shallow water of your local break the waves will be bigger. Longer periods between waves normally means larger, more powerful swell.

Shorter periods (between 1 – 7 seconds) mean the swell is weaker and smaller. The waves are smaller, closer together and generate less power. However, the waves can still be fun with shorter periods, meaning more waves for everyone.

There are a number of websites that have charts to forecast the swell, it's a matter of finding one that best suits your location. Happy surf forecasting!

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