How to read a surf forecast (and a surf report)

To read a surf forecast, check four things in order: swell height and swell period (how big and how powerful the waves are), swell direction (whether they can reach your beach), wind speed and direction (whether the face is clean), and the tide (whether your spot works at that time). A 1 m swell at 14 seconds with a light offshore wind is usually a far better day than a 1.5 m swell at 6 seconds with a 15-knot onshore.

Open any surf forecast and you meet a wall of numbers: swell height, period, direction, wind speed, wind direction and tide times. Most people fixate on the first and ignore the rest, which is exactly why they get skunked. The sections below take each number in turn and show how they combine into a wave worth paddling for.

How do you read a surf forecast?

A surf forecast is read as a stack of conditions that must line up at the same hour: swell height and period for size and power, swell direction for access to your beach, wind for surface quality, and tide for how the spot breaks. If one of those fails, the session suffers, however good the others look.

A practical order of play:

• Step 1, period: below about 8 seconds expect weak, crumbly windswell; 10 seconds and over means real wave power.
• Step 2, height: judge size against your ability, not against the headline number.
• Step 3, direction: check your beach faces the swell and is not shadowed by a headland.
• Step 4, wind: offshore or light is the aim; strong onshore usually means a blown-out sea.
• Step 5, tide: match the hour to the part of the tide your spot prefers.

What do the numbers on a surf forecast mean?

The main numbers on a surf forecast are swell height (in metres or feet), swell period (seconds between waves), swell direction (the compass bearing the swell comes from), wind speed (usually knots) with wind direction, and tide height or times. Together they describe how much energy arrives, where it comes from, and how the local weather and water level shape it.

Many forecasts add extras such as gusts, sea temperature and a secondary swell. These are worth a glance, but the first five numbers decide whether a spot is worth the drive.

What is the difference between swell height and wave height?

Swell height is the size of the waves in the incoming swell, measured offshore before they reach the coast, while wave height is the size of the waves you see at the break, or the total sea state once local wind chop is included. The two often differ because waves grow, shrink and bend as they reach shallow water.

Forecasters usually quote significant wave height, which is the average of the highest third of waves, so the biggest sets will be noticeably larger than the figure. A beach also rarely matches the offshore number exactly: a sheltered bay can show less than the forecast and an exposed reef more.

On its own, height tells you surprisingly little. A 1 m reading can mean a fun, playful day or a weak, gutless one depending entirely on the next number, the period.

What swell period is good for surfing?

A swell period of 10 seconds or more is good for surfing, and 12 to 16 seconds is where the best days live, because longer-period swell carries more energy and forms cleaner, more powerful waves. Period is the time in seconds between successive waves, and it is the most under-rated figure on the forecast.

• Short period (6 to 9 s): locally generated windswell. Weaker, more crumbly, closer together. Fine for learning, underwhelming for experienced surfers.
• Medium period (10 to 13 s): the bread and butter of most good sessions. Enough power to form a proper wave.
• Long period (14 s or more): groundswell that has travelled across the ocean. Deceptively powerful: a "1.5 m at 16 s" will break far bigger and harder than the height suggests.

Rule of thumb: the longer the period, the more the wave over-delivers on its stated height. For the full story, read swell period explained: why a 14-second groundswell surfs nothing like a 6-second windswell.

What does swell direction mean, and why does it matter for a spot?

Swell direction is the compass bearing the swell is travelling from, so "W 270°" means waves arriving from the west. It matters because a beach only receives swell from the directions it faces: a headland, island or sandbank can block the energy completely, so a big swell from the wrong direction can leave a spot flat.

Every break has a swell window, the range of directions that reach it cleanly. A north-facing bay needs northerly swell; a west-facing beach wants westerly. Learning your local windows is one of the most useful bits of local knowledge, and it is the hardest to pick up from a generic forecast. Some spots also work only with a narrow band of directions even when others are open.

What wind is best for surfing: offshore or onshore?

Offshore wind is best for surfing: wind blowing from the land out to sea holds waves up and grooms the face clean, ideally at under about 10 knots. Onshore wind, blowing from sea to land, flattens and crumbles waves, and a strong onshore of more than about 15 knots has usually blown the spot out.

• Offshore: holds waves up and grooms them. The dream. Light offshore or glassy conditions are what dawn patrols chase.
• Onshore: flattens and crumbles waves into mush. A strong onshore can ruin an otherwise perfect swell.
• Cross-shore: somewhere in between. Workable, especially if light.

Strength matters too: under about 10 knots and direction barely bites. Wind also tends to be lightest at dawn at many coasts, which is part of why early sessions are so often the best.

How does the tide affect surf?

The tide changes the water depth over the sandbar, reef or beach, so it changes how, and whether, a spot breaks hour by hour. Many beaches only work on a particular part of the tide: some are best around mid-tide, some break well only at low, and some close out or go flat at high.

A rising tide can switch a spot on or off within an hour, so always read the tide curve against the swell, not in isolation. Local knowledge helps a great deal here; ask in the surf shop or school, or note when your spot is at its best over several sessions. Remember too that a big tidal range makes beaches in places such as Cornwall and Brittany look completely different at low and high water.

What is the difference between a surf forecast and a surf report?

A surf forecast is a model-based prediction of swell, wind and tide for the hours and days ahead, while a surf report is a description of what the surf is actually doing now, usually written by an observer or read from a live camera. Use the forecast to plan, and the report (or your own eyes) to confirm.

In practice the two terms are often used loosely, and many sites blend them. The thing to remember is that a forecast is a prediction with some error, which grows the further ahead you look, while a report is a snapshot. The best routine is to check the forecast the evening before, then look at a camera, a report or the beach itself before you paddle out.

What do star ratings and surf scores mean?

A star rating or surf score is a single summary of how good the conditions are, compressing swell, wind and tide into one figure so you do not have to decode every number. It is a convenience, not a guarantee, and different services weight conditions differently, so a rating from one site does not equal another's.

4Shor shows a surfing score from 0 to 100 for each hour, for each of four ability levels: beginner, intermediate, advanced and expert. For surfing, the score compares wave height with an ideal range for that ability, takes in wave period, and uses a modelled breaking condition (peeling, crumbling, closing out, dumping or surging) from the ShoreSense wave model. It does not use tidal currents, so check the tide yourself. The forecast also shows gusts and sea temperature alongside the score; the score does not account for them, so look at them too.

See it on the surfing forecast.

What is a good surf forecast for beginners?

A good surf forecast for beginners is small and gentle: waves of roughly 0.5 to 1 m, a short to medium period, a light offshore or cross-shore wind under about 10 knots, and a forgiving sandy beach rather than a reef. Bigger, longer-period swell is more powerful and harder to paddle into, which is why it suits more experienced surfers.

This is a rule of thumb, not a safety guarantee; always check local hazards, rips and flags, and surf where lifeguards are present if you can. For more on choosing conditions and equipment, see our surfing for beginners guide.

How do you put the numbers together?

A genuinely good surf day is a stack of conditions lining up at once: the right swell size and period, from a direction your beach faces, on a workable tide, with light or offshore wind. Miss any one and the session suffers.

That is a lot to cross-reference for every beach in range, which is why many surfers lean on a score for a first filter and then read the underlying numbers for the spots at the top. Whichever tool you use, the same five checks apply: period, height, direction, wind, tide.