Checking a surf forecast can feel like reading a foreign language. Wind at 8 kts offshore, 4–5 ft at 14s, NW swell — what does that actually mean for your session? Here’s everything you need to know.
The three numbers that matter most
Every surf forecast boils down to three variables: swell height, swell period, and wind.
Swell height
Swell height is the wave face size you’ll see in the water. A 4 ft swell at your local beach break might be a fun waist-high day; that same 4 ft at a reef that jacks up could be well overhead. Always contextualise height by the spot.
Rule of thumb: wave face = roughly 1.5× to 2× the swell height, depending on the spot’s bathymetry.
Swell period
Period (measured in seconds) is the time between successive wave crests. This is the number beginners most often ignore — and the one that matters most.
- < 8 seconds — wind swell. Short, choppy, crumbling walls. Messy.
- 8–12 seconds — mixed. Can be fun, can be frustrating.
- > 14 seconds — groundswell. Clean, powerful, well-organised lines. This is what you want.
A 3 ft swell at 16 seconds will surf much better than a 5 ft swell at 7 seconds.
Wind
Wind is what separates a good day from a great one.
- Offshore wind (blowing from land to sea) grooms the faces, holds them up, and creates that classic clean, glassy look.
- Onshore wind (blowing from sea to land) chops up the surface and causes waves to close out faster.
- Cross-shore wind is in between — acceptable at lower speeds.
Zero wind and glassy conditions are the gold standard.
Secondary variables
Tide
Tide affects how waves break over a particular bottom. Most spots have an optimal tide window — often mid-tide on the push or pull. A beach break that’s incredible at mid-tide can be flat and closing out at high, or slow and crumbly at low.
Learn your local spots’ tide preferences; it’ll pay off more than any gear upgrade.
Swell direction
The angle the swell is travelling determines which spots light up. A SW swell that wraps around a headland might deliver perfect peelers to a sheltered cove while leaving an exposed beach completely blown out. Check a swell map and understand your coastline’s orientation.
Putting it together
The best surf sessions share a pattern: long-period groundswell + offshore wind + the right tide for your spot. Chase all three at once and you’ll rarely be disappointed.
Element’s conditions score does this calculation for you automatically — factoring in each variable’s weight for your specific spot. A score above 75 means conditions are genuinely good. Below 40 and you’re probably better off waiting.
Want conditions scores for your local breaks? Download Element on the App Store.