Whether you’re a beginner surfer or a pro rider, the term ‘wave period’ will have come up in the post-surf, beach bar chats at least once in your surfing career.
In short, the wave period is the time (measured in seconds) between two waves. The top (crest) of the waves to be exact.
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What is the definition of wave period?
Wave period is defined as the time it takes for two successive crests of a wave to reach a fixed point. Simply, the time in seconds between the two highest points of the wave.
The highest points of the two waves shown below are marked with pink arrows.
The distance, in time, between those points is defined as the period between the waves.
Why does the wave period matter?
The larger the wave period the more time the wave has to accumulate energy over time.
Meaning the wave is more powerful when it reaches its destination and can cope with other surf-destroying factors such as winds, tides, and currents and will be a more efficient and powerful wave when it hits the break.
The wave period is important as it gives you an indication of what kind of waves you can expect. Something every surf forecast reader needs to know.
The wave period can change by a mere second and the surf conditions can be incredibly different from day to day.
Bigger periods equate to better surf. Here’s why.
The bigger the distance between the waves the more energy they have. This is helpful for surfers for many reasons such as having an easier paddle out because you’re not fighting relentless breaking whitewash waves. The bigger the period the cleaner the surf, generally speaking.
What’s the difference between wave period and wave height?
The wave period is the time between the peak of each incoming wave.
Wave height is the vertical distance between the highest peak of the wave and the lowest part of the wave, called the trough. Normally measured in ft. Wave height is how tall the wave is when it stands up when it hits the beach.
Wave period and wave height both contribute to the type of wave produced but are very different.
You can have a big wave height and a low wave period but that won’t necessarily mean you’ll have good surf conditions.
Large wave height isn’t the only metric that makes for a fun surf.
The wave height is illustrated in the above image as the distance between the two pink arrows.
What to look for in a wave period for surfing
When you’re looking at the surf forecast, or looking at the water from the land, the longer the time frame between the waves, the better. This metric will determine a large percentage of how good the surf will be, but not all of it. We will go more into this in what other factors affect the surf section.
So, what is a good swell period for surfing? What you’re looking for in the wave period is anything above 10 seconds. A frequency below 10 seconds is defined as wind slop.
Wind slop means pretty un-surfable conditions where it would be hard to make out individual waves and you’d be facing a large volume of whitewash.
Anything above 10 seconds means the power of the larger wave period will generate better-quality waves.
|Wave period||Wave type|
|Under 5 seconds||Known as very messy and un-surfable conditions, hard to identify individual peaks and sets and lots of white water to be seen.|
|6-8 seconds||Messy surf conditions, not high quality but offshore wind direction and good swell directions for the location can make this a better session. Not often very clean.|
|8-10 seconds||Higher quality surf conditions. Able to make out individual waves easily and see the shoulders of the waves for good surf due to the medium length period.|
|10-12 seconds||Paddle-outs become more manageable, but the sets tend to be bigger on bigger swells at this period due to more energy being in the water. High-quality, clean and powerful waves are coming at this frequency.|
|13 + seconds||Anything above 12 seconds is set to be an epic forecast if each weather element falls into place. The waves will have the longest time between each other making waves super awesome when you drop in.|
You might like to read our article about how to make surfing easier >
What affects the wave period?
The wind strength and direction out at sea affect the wave period.
When the wind blows on the sea the wind’s energy transmits its power into the water, and then these waves will travel up to hundreds of kilometres until they reach the beach they break on.
As the waves travel over distances, they form into more consolidated waves.
Groups of waves interact and they either get bigger or they cancel each other out.
So, in short, big storms with lots of energy far out to sea equates to power in the ocean and hopefully a big wave period. But this can be destroyed by tides, currents, other winds, and other wave groups.
What other factors affect the surf?
Remember, the wave period is only a puzzle piece in the jigsaw of the good wave quest. So many other elements have to be working to get good surfable waves such as; wave height, sets, swell height, swell direction, wind strength, wind direction, and currents.
You then have the type of beach that the wave is hitting, like point breaks or beach breaks. This is a whole nother kettle of fish, but a healthy wave period is a good indication of a good session ahead.
Check those digits and get suited up for anything above ten seconds. Happy surfing…
About the author
Watersports Pro is managed by Ollie, who has been in the industry since 2007. A paddleboard and advanced windsurfing instructor, Ollie has travelled the world teaching these sports.
Now based on the South Coast of England, he shares his experience and knowledge on watersportspro.co.uk.