Swell Height π Surf Height
First off we need to make an important announcement:
Spoiler Alert
Sooo what's the difference and why should I care?
Swell Height
The word swell is commonly used to refer to waves traveling in the open ocean. You can think of "Swell height" as the size of the waves you would see if you're on a boat.
Surf Height
When swell in the open ocean reaches the shore, it turns into a breaking wave that you can surf. So "Surf Height" is how big the waves are at your local beach. This is what we care about as surfers.
One More Time for the Table Freaks π
| Who | What | Where |
|---|---|---|
| Swell height | The height of waves traveling in the open ocean | What you'd see from a boat β΅οΈ |
| Surf height | The height of waves breaking at your beach | What you'd see at the beach ποΈ |
Totally Different Things
Here's the kicker: surf forecasting sites don't always tell you which one they give you!
This is a big problem, because what's happening out in the ocean is vastly different from what happens at your beach.
Which Forecasting Sites Give You What?
| Forecast Service | Gives You | |
|---|---|---|
| Swellify | Height of waves you'd surf | β |
| Surfline | Height of waves you'd surf | β |
| Swellmap | Height of waves you'd surf | β |
| Windy | Height of swell in the open ocean | β |
| Windy.app | Height of swell in the open ocean | β |
| Surf-forecast.com | Height of swell in the open ocean | β |
| Good Surf Now | Height of swell in the open ocean | β |
The sites that give you swell height (the height of open ocean waves) aren't inherently bad, but keep in mind:
π Estimating the SURF height (size of the waves at your beach) based on SWELL height can be incredibly difficult.
It requires deep knowledge of each surf break and complex formulas that take into account the conservation of wave energy, like this one:
π So if you're using a site that's showing you swell height and not surf height, the forecast can be extremely misleading. Swellify does all of these advanced calculations so you don't have to.
A Tale of Two Swells
There are two swells at sea with the exact same Swell Height. However, one swell approaches the beach from an angle, while the other approaches it head on.