How to Read Waves & a Surf Forecast

Swell height: how big

Wave (or swell) height is the obvious number, but it is the least useful on its own. A "1 meter" forecast can be a fun, clean waist-high day or a messy mush depending on the other factors. As a beginner, you want small and clean, think knee to waist high whitewater and small green waves, not size. Bigger is not better while you are learning; it is just heavier and more dangerous.

Swell period: the quality clue

This is the number most beginners ignore and shouldn't. Swell period is the seconds between waves, and it tells you where the swell came from:

• Long period (~12 seconds or more): a groundswell, organized, powerful waves from a distant storm. Cleaner, more predictable lines.
• Short period (~8 seconds or less): a windswell, weaker, choppier, less organized waves from local wind.

Two days with the same height surf completely differently depending on period. Learn to read period right after wind.

Wind: the day-maker

Wind is often the difference between a great session and a washing machine:

• Offshore (land to sea): best, holds the wave face up and grooms it clean. This is why dawn sessions are prized, wind is often lightest or offshore in the morning.
• Onshore (sea to land): messy, bumpy, crumbly surf.
• Cross-shore: in between; light or no wind is also good.

A forecast with offshore or light wind is usually the one to chase.

Tide: on and off

Tide changes the water depth over a break and can switch a wave on or off. Many spots only work well on a particular tide (say mid, or a pushing tide); some get too fat at high or dangerously shallow at low over reef. As a beginner, ask locals or a surf school what tide your beach works best on, and avoid very low tide over reef. The forecast lists tide times and heights.

Wave types: where it breaks

• Beach break: breaks over sand, the most forgiving and best for beginners (though sandbanks shift).
• Point break: wraps around a headland for long, predictable rides, often more advanced and crowded.
• Reef break: breaks over coral or rock, powerful and shallow, for experienced surfers.

Start on beach breaks and progress from there, and read our surf etiquette and safety guide before any busy line-up.

The fifth thing to read, and it is in the water, not the forecast

Height, period, wind and tide tell you what the day will be like. None of them tells you where the water is going once you are in it, and that is the one that decides whether you spend the session surfing or swimming.

NOAA defines a rip current as a “strong, narrow, seaward flow of water that extends from close to the shoreline to outside of the surf zone”, and gives the signs to look for from the beach: “darker, narrow gaps of water heading offshore between areas of breaking waves and whitewater”, “narrow regions of choppy, rippled water heading offshore”, and “plumes of sand or foam offshore of the breakers”. Two practical notes from the same source: look from an elevated position, and wear polarized sunglasses, which make the colour contrast readable.

The speeds are the part people underestimate. A channel rip “typically flows about 1 to 2 feet per second and may reach speeds up to 8 feet per second”, which NOAA notes is “on par with the top speeds of some of the fastest Olympic swimmers”. Hence the warning that matters more than any forecast reading: “attempting to swim back to shore against the seaward flowing current can quickly result in exhaustion”.

For a surfer the same feature is two things at once. The dark gap with no breaking waves is a hazard for the swimmers on either side of it and a free ride out the back for you, which is why experienced surfers paddle out in exactly the water everyone else is told to avoid. That only works if you meant to be there. Find the gap from the car park before you change, decide whether you are using it or avoiding it, and check it again after the tide has moved, because the channel moves with it.

Putting it together: reading a forecast

Forecast sites like Surfline and Windy show height, period, swell direction, wind and tide. Scan them in the smart order: wind, then period, then height, then tide. A good beginner day looks like small, clean waves, a decent period, offshore or light wind, and the right tide. Big height with short period and onshore wind is usually a mush to skip. When in doubt, ask a local surf school, they read the same forecast every day.