4 Online Tools to Predict Waves + Surfing Conditions

Predicting Waves

Author: Bridget Thorpe
Reading Time: 10 minutes

Years ago, pre-Netflix, Hawaii had a popular TV guide channel.  I think it was channel 3.  There was a very monotone, robotic voice that would play over, and over, and over in the background.  “East, Northeast.  East, Northeast.”  You’d hear it multiple times per day. 

I eventually figured out the monotone voice was reading the weather and surf reports.  Hawaii has a lot of surfers.  And surfers want to know the weather because it helps them predict wave conditions.  So on the TV guide channel, the radio, the news—everywhere you turn—you’re bound to hear a surf report out here.      

In this blog, we dive into the top websites and apps that help skilled watermen and women read ocean conditions.  Data availability will vary based on global region, and this approach is but one way to connect with the swells.  Our goal is to share insight into how some seasoned surfers leverage oceanic data so you have more tools to take your wave search to the next level. Let's jump in...

Step 01 |  Start with Surf Apps

The apps are always a great place to start.  Surfing apps will essentially tell you how big the waves are, weather conditions, and forecasts for the week ahead.  Many also include webcams, helpful features, and a range of fun surfing content.  Our two favorites are Magic Seaweed and Surfline.  

magic seaweed
Magic Seaweed

A personal favorite.  Magic Seaweed has a very robust free version.  It includes a large library of surf spots, so you’ll likely be able to find a good report near your favorite break.  The interface is very user friendly, too.

 

surfline

Surfline

Another great bet.  It has a free version, but you can only look at it so many times until it pushes you to upgrade.  However, you get what you pay for, and the subscription does provide an incredible experience.  It’s another classic and trusted option touted by many pro surfers.    

We love surf apps.  They provide digestible information for your local break and insight on what type of conditions to expect.  More often than not, the app data will be all of the information you ever need.

However, if you are a science buff or interested in understanding wave conditions very deeply, stay with us… 

Step 02 | Check Weather Reports

Although surfing apps have weather reports, you may also want to refer to a few weather sites to diversify your data.  Or heck, see different pictures.  

We love Windy.com.  It’s free and has a simple user interface.  It’s my 75 year-old dad’s favorite—and he still crushes it on the North Shore.  

Weather Report

When reading a weather report, you’ll be looking for 2 main things: wind direction and barometric pressure.  

Wind Direction

Let’s start with wind.  Waves are fundamentally created by wind blowing over the water.  The distance the wind blows over the water is called the fetch.  To create surfable waves, you need a fetch of about 1,500 to 2,000 miles.  

Now, when you’re looking at weather reports like Windy.com, you’re looking for the wind direction.  You want the wind to be blowing offshore.  Or in other words, picture yourself standing at your favorite break looking toward the horizon.  Ideally, the wind will be at your back and blowing your hair toward the water.  Away from the shore.  

Offshore winds are a surfer’s dream.  They hold the waves up and keep them from breaking, which is ideal.  Offshore winds tend to yield groomed, pretty, surfable waves.  

Onshore winds on the other hand (where the wind is blowing toward the shore) don’t produce the best conditions.  They create white caps in the water, as well as crumbly and irregular waves.

Your ideal wind direction all depends on where your favorite break is.  So for instance, many California breaks face directly west.  Here, you’ll want winds coming out of the east and blowing toward the west.  AKA, off the shore.  

Wind direction is something you’ll need to ask around or feel out.  However, once you narrow in on your ideal wind direction, you’ll know exactly what you’re looking for in the weather report. 

Oh, and there’s also wind speed.  Another area we could go deep.  However, no wind will result in glassy conditions.  A glassy day is pretty tough to beat.  

Barometric Pressure

Next up, barometric pressure.  Those big rainbow-colored blobs on maps when you watch the weather channel.  

Lower pressure means bigger storms.  If you look at a weather map and see a purple or red blob, that means there’s a low pressure weather system and a big storm in the works.  AKA, bigger waves are coming.  This may be a good thing for you, or a signal to wait it out until the storm passes.  

Step 3 | Refer to the Tides

Ok, so you’ve checked your apps and you’ve skimmed the weather report.  You’re doing incredible!  Let’s talk about tides.

Tide Calendar

Ideal tide conditions will all depend on your preferred break.  Some spots break better during a high tide, others a low tide.  It’s another thing you’ll have to feel out or ask around for deeper insight.  

What’s good to keep in mind is the tide will relate to the amount of energy in the water.  Generally, when the tide goes up it adds more energy to the swell.  After the tide peaks and starts to go down, that decreases the energy in the swell.  

So, as a very general rule of thumb, you can surf bigger waves during an outgoing tide and feel a bit more comfortable because the energy in the water is going down.  

You find data on tides in surfing apps or weather websites.  Tide calendars are also popular and can be found at a local surf shop.  There are also a lot of watches that include digital tide calendars.  

Step 4 | Level-Up with NOAA Data

We’re going to kick it up a notch now.  You are a brilliant and intelligent woman.  So let’s go to a leading root source oceanic data.  What some of the most seasoned surfers use.  We’re going to NOAA.  

NOAA stands for National Oceanic and Atmospheric Administration.  It is a branch of the United States government.  So, this is a U.S.-centric source, yet it has global data.  It turns out their weather website (weather.gov) is a solid surfing resource for some areas.  Simply type in “NOAA surf forecast [your region/town]” in a Google search.  You can also jump to the global buoy map here, click on yellow diamond near you, then click "view details".  We'll get to more on buoys in a minute...     

Since it’s government data, it’s not the most digestible format.  We’re going to walk you through what to look for so the data doesn’t hit you in the face quite so hard at first glance.  

Surfing Data NOAA

The Discussion

The first thing you will likely see is the discussion.  This section will give you a ~200 word summary of what the waves are going to be like for your desired area.  It’s pretty easy to understand, and it’s updated daily.

The Forecast

Next up is the forecast.  The forecast is a small table that reports the size of the waves (in feet) for today and tomorrow.  Weather, tide, and sunrise/sunset data will be right underneath the table.  

The Buoys (Under Additional Resources)

Now we’re getting into the heart of things.  If you scroll down to Additional Resources, then keep scrolling a bit more toward the bottom, you will likely find the buoy section. (And if you're having trouble finding it, simply start with the global buoy map here.)

What’s a buoy?  A buoy is a floating station stacked with meteorological equipment.  NOAA manages most buoys that we know of.  Buoys are placed off of the shore to provide oceanic data and warnings regarding tsunamis, hurricanes, storms, and other major weather events.  

NOAA records and reports data from the buoys every day—even every hour.  So, when you’re on the website, you can trust the information is both accurate and up to date.  

In the buoy section of the site (or via the global buoy map here), click on the buoy that is closest to the area you typically surf.  The buoy will normally have a location name or number associated with it.  

When you click on your buoy link, it will take you to the buoy station data page.  You’ll likely see a map in the top corner with yellow diamonds.  Each diamond is a buoy, and if it’s yellow it means it’s active and the data is current.  If it’s red, the data isn’t up to date.  

Pro tip:  On this map, you’ll likely find a buoy relatively close to your local surf spot.  But, if you know the direction the weather is coming from, you can also zoom into buoys that are farther off of the shore.  These buoy readings will give you an indication of the type of waves that are on the way.     

We’re in the home stretch.  On your buoy page, you’ll scroll down a bit and see a table.  What we’re doing now is narrowing-in on wave period and wave size. 

Surfing data NOAA

Wave period is the time between wave peaks.  Or, crest to crest.  Or, the top of a wave to the next top of a wave.  Generally, the longer the wave period, the bigger the wave.

Wave size is what it sounds like.  It’s how tall the wave is.  The distance from top to bottom.  Crest to trough.  

You need to use a bit of your spidey senses to interpret the wave period and wave size data.  We’ll review an example in a second.  Back to the charts.  

See the right triangles at the top of the wave chart?  The ones with rows of hourly data beneath them?  Here’s what to focus on:

  • WVHT = Wave Height.  It’s measured in FEET.  It’s the height of the waves coming.
      
  • DPD = Dominant Wave Period.  It’s measured in seconds.  This data point looks at the longest periods.  It’s telling you the average period of the biggest sets coming in. 

  • APD = Average Wave Period.  Again, measured in seconds.  Average is, well, what it says.  It’s the average wave period of all of the waves over the last hour. 

  • MWD = Mean Wind Direction.  This is telling you the direction of the wind.

  • WTMP = Weather Temperature.  You got that one.   

To predict the size of the waves coming, we like narrowing-in on the relationship between WVHT and DPD.  This part is where your spidey senses come in.  For example:    

If it’s 5 feet and 10 seconds, that means the waves are about chest to head high.

If it’s 5 feet and 20 seconds, that’s probably a double overhead wave.  

See what happened there?  The WVHT stayed the same, but the DPD increased.  So the waves got bigger.  Because the longer the period (or the more seconds), the bigger the wave.  Generally speaking, of course.  

Like everything we’ve reviewed so far, each surf break is going to have its own magic numbers.  And weather reports and data availability are not always 100% reliable.  Yet, with a bit of time, it can be fun understanding what kind of data you like to surf.  As you gain confidence reading the data for your favorite surf spot, you’re on your way to predicting wave quality around the world.  

Honorary Mention | Webcams

Last but not least, the webcam. You can find webcams via surfing apps, lifeguard stations, hotel websites, surf shops, fruit stands, and a whole host of random locations.    

Once you find a good webcam that faces your favorite surf spot, it’s an easy way to check the waves in real time and save you the drive.  

We are passionate about science-based resources.  We hope this blog boosted your confidence on one way to read surf swells and make sense of various weather reports.  We also get science-y while talking about our Responsibility Practice, our carbon footprint, and how our hybrid sports bras are made.  Dive in here for additional knowledge and check out our styles.