What Is the Definition of Background Swell?

Background swell, otherwise known as impulse swell or wind swell, is a classification of wave and a term often used in surfing forecasts.

  1. Types of Swell

    • Surfing terminology refers to groundswell and wind swell --- a more commonly used name for background swell. Wind swell is caused by winds in the local area, while groundswell is the result of a weather system farther away. Groundswell and wind swell can be distinguished by the amount of time between each wave, known as the period, as well as their height. Waves with a period of more than 11 seconds are classified as groundswell, while wind swell has a shorter period. The longer the time between waves, the higher the swell will be.

    The Height of Background Swell

    • Surfers often measure the height of waves by comparing it to points on their body. Background swell can reach up to head height (5 to 6 feet) during winter and waist height (around 3 feet) in the summer.

    Swell Rating System

    • According to Stormsurf, a forecasting resource, swell can be split into eight categories, with waves rated zero being the smallest and those classified as seven the largest. Background swell is classified as category one.