Swell is wave energy generated by distant wind. It travels across the Atlantic and changes as it meets the Galician coast. Height is one part of that energy. Period, direction, the seabed, exposure, tide, and local wind decide what the beach actually receives.
Period is the time between waves. A moderate swell with longer period can carry more organized energy and break with more push than a taller, shorter-period swell, especially where the seabed focuses energy into a defined peak. One forecast height rarely describes the day.
Not every coastline faces the same way. A beach open to northwest swell may work while a nearby beach stays weak because the angle is wrong, a headland blocks energy, or the seabed disperses it. Orientation, not road distance, is usually why two spots disagree.
Tide changes how and where that energy releases across the bank. The same incoming swell can stand up, close out, or go fat as the water depth over the sand changes. Read tide with the swell, not after it.
Read swell as height, period, direction, tide, and wind together. One Atlantic pulse can produce different results across exposed beaches, sheltered coves, rías, and headland-protected corners. The forecast is the incoming energy. The beach is the filter.
For surfers, swell period is the time between waves and a cue for how organized the arriving energy is. Longer period often means more powerful, better-spaced sets than a shorter-period swell of similar height, especially where the seabed focuses energy into a peak. Local bottom shape and direction still decide whether that energy becomes a usable wave at a specific break. Read period with height and direction, not as a substitute for them.
One nearby beach can work while another stays flat or messy because they do not face the swell the same way and they do not break over the same bottom. Direction, exposure, tide response, headlands, and local wind all change how the same Atlantic swell translates into surf. Distance along the road is a weak predictor. When the exposed beach is chaotic, the next orientation along the arc is the comparison, not a copy of the first reading.
Written by the Atalaia team. Atlas of the Atlantic. Method at /about.