Swell chart: the red fetch is coming to your surf spot

Surf reports are a result of swell and wind chart analysis. Tracking the direction, strength and duration of incoming waves and winds is a key variable for surf forecasters.

The best swell conditions for great surfing sessions can be easily spotted by everyone. You don't need to be a professional weather forecaster in order to understand how, when and where is the best surf spot for surfing waves.

Waves are a result of the energy applied by winds on the surface of the sea water. The large areas affected by the winds on the oceans are called fetch and are in constant mutation.

When we look at a swell chart, we see circular colored fetch with the correspondent significant wave height. The edges of the fetch will hit our shores in a matter of hours or days. But, can we calculate when will the ground swell reach the shoreline?

It's quite easy. There's a simple math equation. Knowing that a swell will travel, on average, at 1.5 times its period in nautical miles per hour, we only need to check the average wave period and the distance of the fetch. So, if there's a good-looking fetch at 2500 nautical miles heading to our surf spot, with an average period of 15 seconds, the calculation is as follows:

2500 nautical miles X (15 seconds of wave period X 1.5) = 111.1 hours

The swell will hit the shores in 111.1 hours, which means 4.6 days. In four and half days the swell we wanted to track, may offer pristine surfing conditions to your local spot.

Discover the Wave Height Forecast charts where you can find favorable swell and fetch.
Also, take a look at the Wave Period charts where you can check the wavelength.
The Wind Speed and Direction Forecast lets you confirm the direction of the breeze.

Understand how waves are formed.
Learn the difference between ground swells and wind swells.