How to find the period of a wave

The period of a wave or “wave period” in surfing is the time it takes for a series of waves to pass through a specific point. This interval is a key indicator of the quality of the swell and, therefore, a crucial factor in interpreting wave forecasts from our favorite apps. Here, we’ll explain everything you need to know about how to find period of a wave.

wave period

period of a wave formula

  • What is a wave period?

The period of a wave refers to the time it takes for one complete cycle of the wave to pass a specific point. In the context of surfing or oceanography, it specifically represents the time between successive wave crests (or troughs) as they pass a stationary point. This is often measured in seconds. A longer wave period generally indicates more energy and is often associated with larger, more powerful waves. Surf forecasts and oceanographic reports often provide information about the wave period to help surfers and mariners understand the characteristics of the waves they can expect.

  • How to calculate period of a wave?

The wave period is measured in seconds. If the swell has traveled from a long distance, the interval will be longer, and the waves will arrive in closely grouped series with almost total breaks between series. Conversely, if the swell was generated very close to your coast, perhaps due to a wind blowing directly onto the beach, the interval will be much shorter, with poorly defined waves.

  • How does the wave period influence surfing?

In addition to influencing the quality of waves reaching our beaches, the wave period also affects the open sea. The longer the interval, the more reefs in the open sea will affect it. Consequently, the series will travel with a greater angle towards the coast. Each swell moves the sand in a different way.

  • What is the period of a wave in Windguru?

The peak wave period line in Windguru indicates in seconds the period/wait between wave crests. Longer periods are better for surfers. Once again, Windguru uses numbers and colors. Here’s an example:


zarautz wave report Zarautz wave report on Windguru

The period in Zarautz starts on Monday at 10 seconds and rises to 15 by Friday. What does this mean? Without looking at the sea, the forecast for Friday is very good. On Thursday, there will be hardly any wind, leaving the sea orderly for Friday. Also, on Friday, the sea rises, and the period increases.

In general, for all followers of Windguru and Surf Forecast, longer periods mean better wave conditions.

If you enjoyed this post, don’t forget to visit our tag #surfbase where we’ll be showing you different articles to easily familiarize yourself with basic surf vocabulary. You can also subscribe to our newsletter to receive our updates promptly. We hope you enjoyed this article. In our next episode, we’ll talk about how a swell forms and the types of waves that exist.