All sports
Fetch
The unobstructed distance of open water over which the wind blows in one direction — controls how big and clean waves get.
Fetch is the length of water the wind has worked on before reaching your spot. The longer the fetch and the longer the wind blows, the larger and more organised the resulting waves.
A 15-knot wind across 5 km of bay produces a chop you can plane through. The same 15 knots across 1,000 km of open Atlantic produces a swell that breaks as head-high waves a thousand kilometres away.
Fetch is why:
- Offshore winds at a flat-water spot stay buttery — almost zero fetch
- Onshore winds in shallow bays build choppy swell fast
- Forecast models like WaveWatch III simulate wind fields over giant fetches to predict swell days ahead
Related reading: Types of Wind, Tides for Surfers.
Related terms
- Wind gradient The change in wind speed and direction with height above the surface — friction slows wind near the ground.
- Set A group of larger, well-formed waves arriving together after a lull — usually 3–8 waves in a row.
- Sea breeze A daytime onshore wind driven by uneven heating of land and water — the engine of most summer coastal sessions.
- Trade winds Steady tropical easterlies blowing roughly between 30°N and 30°S — the most reliable wind belts on the planet.