How to Read a Surf Report
Before you can surf the waves, you have to find them. It helps to have a basic knowledge of the conditions that generate and shape them. Fortunately, you can find a wave near you by using online surf reports and a few basic rules of thumb.
Your average surf report forecasts waves based on swell direction, wave height and local wind conditions. When they are all in sync, get excited. When one is out of whack, waves and surfers suffer. A bunch of factors play into just how big and well-formed swells are when they reach your beach. Let’s talk about how to understand ocean and surf conditions and how to read a surf forecast so you can learn to gauge what’s coming.
All you need to know about swell direction is how it impacts your surf spot. For example, in California, when a surf report says a west swell is on the way, they are describing waves originating from the west. Assuming your beach faces due west, the swell is on course to hit your break straight-on. If they are forecasting a southwest swell, then the swell will hit your break at an angle from the SW, giving you a different looking wave as it meets your beach, reef or point break. Knowing what swell directions work best for your local surf spots comes with time spent in the water and talking to locals. Checking your favorite surf sites each day doesn’t hurt either.
The number one question is: how big is it going to be? You can look online at your local wave buoys (offshore wave and weather buoys) for this information, but most surf report sites will interpret the important points for you and provide links. To know how to read a surf forecast, you’ll need to understand commonly used terminology, such as swell height and swell interval (time between waves).
“3 feet at 10 seconds” is an example of the average height of waves passing the offshore buoy and the average time between waves as they pass by. Both numbers are critical in judging the size of the waves that eventually hit your local surf spot. However, the swell interval is where you should put your money. A longer interval makes for a larger wave. “3 feet at 4 seconds” is an insignificant wave. “3 feet at 18 seconds” and I’d recommend you call in dead from work. Add a large swell to a large interval (10 feet at 22 seconds) and you can anticipate massive surf. It should be no problem to forecast the size of waves if you apply these basics to your local surf reports.
The size, quality, speed and very existence of a wave depend on your local tides. That’s why you have to factor in the tide cycle to understand ocean and surf conditions at your local beach. Some spots work better at low tide than at hide tide and vice versa. A surf break may be known as a low or high tide spot depending on which tide forms the best-breaking waves.
Beginners take note: just because a spot is known as a low tide break doesn’t mean you can’t have uncrowded fun during a high-tide session. All it means is that the spot works best at low tide. At low tide, sand bars will be exposed to waves that were too deep for breaking waves during high tide. Other spots work better at a higher tide because sand bars may be too shallow at lower tides. In short, tides affect water depth, which in turn either exposes or hides the ocean floor that is necessary for a wave to break. That’s why it’s crucial to factor them into the surf equation.
Waves rely on wind for their birth and quality of life. Plainly put, wind creates waves by transferring energy from the air to the water. Once a swell is created, it travels until it expends its energy on a reef or shoreline. Winds that create good swells are usually formed well offshore, allowing the swell (also known as ground swell) time to build in size and intensity. While there are lots of factors behind the birth of a storm, for our purposes we just need to be aware that they are sending waves our way.
Nevertheless, a solid swell does not always translate into good waves locally. A good day of surfing requires favorable local winds. Understanding the difference between onshore and offshore winds goes a long way in understanding how the swell will look when it is welcomed by your local break.
Imagine you are standing on the beach facing the ocean with a strong breeze in your face. In other words, the wind is blowing onto the shore – onshore wind. An onshore wind is a swell killer in that it takes an organized, clean swell and turns it into confused, choppy surf. Onshore winds come from behind or from the side of the waves, turning a swell into surf that is bumpy and more difficult to ride. Ideally you want what is known as “clean surf.”
A clean wave is one that is lightly fanned by an offshore wind or no wind at all. These conditions are devoid of surface bumps or chop on the wave face, which allows you a smooth ride. Offshore winds, winds that blow off the shore and into the coming waves, groom waves by lightly holding them up before they break. The only wind better than offshore wind, when swell is in the water, is no wind at all. A swell that is met with no wind results in a glassy day, a day when the surface of the wave resembles glass. Aesthetically and viscerally, a clean swell is the thing of surfer’s dreams. Skiers and snowboarders live for powder, while the surfer lives for the glassy day.