How to Read Buoy Reports

April 26, 2010

There’s no doubt that the dawn of the internet-age has affected the sport of surfing immeasurably. Gone are the days of showing up to the beach with little more insight than a coastal flag-pole whipping in the breeze. Today we have constantly updated, highly detailed swell and weather forecasts that tell us everything we want to know about the day’s surf scenario. And of course, if all else fails, we can always log on to the old interweb and check out a live beach camera just to be sure.

But does the modern era of online surf reporting necessarily mean there is no longer a need for surfers to understand, at least on a fundamental level, the interrelated dynamics of weather, wind, and swell? Are buoy reports and swell maps completely outdated? You need only ask a man of the sea – be it a knowledgeable surfer, sailor, or fisherman – to realize the answer is unequivocally no.

Many a beginner surfer has puzzled over a seemingly inaccurate surf report. “But my online wave-forecasting tool said the surf was supposed to be fair-to-good today,” an unaware and unschooled surfer may utter as he stares blankly at a mediocre, if not totally un-rideable ocean. Tisk, tisk. Here is a golden rule: He who does not understand the ocean shall be skunked. Repeatedly.

Taking a little time to improve your ocean IQ will almost certainly prove a fruitful venture, allowing you to not only avoid undesirable surfing conditions, but also increasing your scoring drives to the beach. Heed these lessons carefully, young grasshopper.

The Buoy Never Cries Wolf

Well, unless it’s not functioning correctly or a huge sperm whale happens to swallow it. But under normal circumstances, the automatically updated data transmitted by a working buoy will give you accurate information on local surf conditions. Most of the buoys in the United States are run by the National Oceanic and Atmospheric Administration’s (NOAA) National Data Buoy Center. Individual buoys can be accessed on the internet via NOAA’s website. Here’s how to read them:


Wind, and more precisely, where it’s coming from and how fast, is the second most important surf-affecting variable other than wave size. It’s also constantly changing and difficult to predict with much precision. Because onshore wind (blows from the ocean towards land) is detrimental to surf conditions, and conversely, offshore wind (blows from land out to sea) is optimum, it’s a good idea to understand how to get up-to-date wind information from your local buoy.

The two variables that influence wind conditions are wind direction and wind speed, and both are important. Wind direction tells you the direction the wind is blowing from. Wind speed is the speed the wind is blowing, measured in knots. For example, if the buoy’s wind reading says the direction is NNW at 15 kts with 25 kts gusts, that means the wind is blowing out of the north/northwest, at 15 knots, with occasional gusts of up to 25 knots. For surfing, that’s a lot of wind, but if you have access to a break that faces south, the wind will funnel straight offshore.


This one takes the top honor in terms of importance to the surfer. If there are no waves, it really doesn’t matter what the wind direction is or how high the tide is – you’re not surfing anyway. And while all the surf-forecasting websites do a pretty decent job of giving you accurate swell information, any individual swell event goes through a lifespan that ranges from building, to peaking, to dying out, and eventually fading completely. Check in with your local buoy to see exactly what the swell is doing at that exact hour.

There are two variables that contribute to the size of a wave when it breaks: wave height and wave period. What? There’s more to waves than their height? Oh, you have so much to learn.

The period describes time elapsed between individual waves within a given wave set. For example, a period of 14 seconds means that when a set of waves reaches the beach, about 14 seconds will elapse in between each wave that breaks. Interestingly, a wave’s period is extremely significant because it directly affects both size and power. Period translates into the distance between two waves as well as the depth, meaning the longer, or deeper, a wave’s period, the bigger and more powerful it will be once it reaches its breaking point. Therefore, a wave with a long period will actually have more deep-water energy than a wave with a short period, giving it more height and power when it breaks.

A buoy’s wave height reading is exactly what it sounds like: the height, given in feet, from the peak of each wave to its trough. Keep in mind that buoys will automatically average out both the wave height and wave period.

So how do you determine actual wave height from both size and period? To know how a certain swell will affect your local surf conditions, you need to understand how particular breaks respond to both short period swell (also called wind swell) and long period swell. You also need to quantify the height and period into a single overall estimation of wave height. While experience is the only way to get really good at determining this somewhat elusive value, you’ll quickly learn that a swell reading six feet at 18 seconds is a lot bigger than one registering 10 feet at eight seconds.


In addition to wind and wave height, buoys also compute both air and water temperature. While these are certainly important factors when deciding which wetsuit to wear or how long you’re going to be sunbathing on the beach, they don’t really contribute to wave quality.

Other Factors: Tide & Swell Direction

Tide and swell direction are secondary factors when determining surf quality, although both are extremely important. Blissful ignorance to tide and directions will only be blissful for so long.

Swell direction is an obvious factor when deciding when and where to surf. If a moderate-sized swell is rolling in from the south, you shouldn’t head to a beach that faces north unless you want to do more fishing than surfing. On larger swells, it’s sometimes wise to check spots that aren’t openly facing the brunt of the swell in order to access friendlier waves.

Ever wonder why surf shops give out those little tide books at the front counter? Every surfer should be aware of the day’s tidal scenario when deciding when and where to surf. Most surf spots have a particular tide that works best with that spot, and outgoing and incoming tides can affect rip currents and wave consistency. While some breaks may function on any tide, many more will altogether shut down if the tide is too low or too high. Getting to know your local surf spots and what tides they prefer is an important step towards getting quality surf as often as possible.

Learn & Surf

Becoming an expert on local surf conditions won’t happen overnight, but with open ears and a little bit of empirical research, you’ll quickly become acquainted with what your area has to offer. Learning how to properly read buoy reports will make you less reliant on the many over-generalized and under-detailed surf reports lurking on the internet, ultimately increasing your chances of scoring perfect, un-crowded surf.

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