02/06/2026
The wind in the midst of storms usually blows in intervals, which we call gusts. The primary swell-producing component of wind is consistency. So the lower, sustained, most consistent end of the wind speed spectrum is what really generates the swell. But still, the more the wind gusts above that range, the more that energy is transferred into the water. Once the swell leaves the storm-generating area, the swell energy bonds together and travels in groups of waves we call sets. The waves within the sets cycle together with other waves, which helps to conserve their energy over vast distances of ocean.
So how come some sets arrive every 15 minutes with only one or two waves, and other sets arrive every 5 minutes with 10 waves in each set? One part of the answer goes back to the wind. Low pressure systems without a solid high pressure system filling behind in the low will result in very gusty, flukey winds. The winds may range between 20-50 knots but aren’t sustained enough to transfer enough energy into the water. As a result there may be some big waves, but the number of waves per set will be less, and the consistency of the sets will be less frequent.
On the other hand, strong high pressure following a storm creates stronger, more consistent sustained wind speeds which will not only result in a bigger swell, but also more waves per set and more consistent sets.
A second part of the answer is the length and “width” of the fetch, which will combine with the consistency of the sustained wind speeds to determine the number of waves per set as well as the consistency. Everybody knows fetch length is an important component, but the width of the fetch plays a huge role in the number of waves per set and the set consistency.
A third part of the answer is how centered the swell focus is on your spot. If a swell coming up from the Southern Hemisphere is centered on a region, this is where you’ll find the maximum energy, which is the maximum number of sets and the most waves per set.
As you move away from that center, you get out on the edge of the swell. As a result you find less consistent sets and less waves per set.
Continued in comments…
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