How to Read a Surf Forecast

Level: Beginner8 min read

Wave height, swell period, swell direction, wind, and tide — here's what surf forecast numbers actually mean and how to use them to pick a good session.

Surf forecasts can look like a wall of numbers, arrows, and colors. Wave height, period, direction, wind speed, tide charts — it’s a lot. But once you understand a few key ideas, forecasts become one of the most useful tools you have for finding good waves and staying safe.

This guide breaks down the main pieces of a surf forecast in plain language, and explains how to use them together.

Why Forecasts Matter

The ocean changes every day — sometimes every hour. A beach that’s perfect in the morning can be blown out by afternoon. A forecast helps you:

Pick days with waves that match your ability
Choose the best time of day to go
Avoid conditions that are too big or dangerous
Understand why a session was great (or wasn’t)

Forecasts aren’t perfect. They’re predictions, and local conditions can surprise you. Always check the actual ocean before paddling out.

Wave Height vs. Face Height

This is one of the most confusing parts of surf forecasts, so let’s start here.

Swell Height

Many forecasts and ocean buoys report swell height — a measurement of the swell out in open water, before it reaches the beach. Buoys usually report “significant wave height,” which is a statistical average of the larger waves in a set of measurements.

Swell height is useful, but it isn’t the same as the size of the waves you’ll actually ride. As swell reaches shallow water near the beach, it can grow, shrink, or change depending on the ocean floor, the beach angle, and the swell period.

Surf Height (Face Height)

Many surf forecasts translate swell into surf height — an estimate of how big the breaking waves will be. This is often described by the wave face: the height of the wave from its bottom (trough) to its top (crest), on the side you’d ride.

Forecasts often describe size in relation to the human body:

Ankle to knee high: very small
Knee to waist high: great for beginners
Waist to chest high: fun for many surfers; can be challenging for brand-new beginners
Head high and bigger: generally for intermediate and advanced surfers

Why Numbers Can Be Confusing

Different surfers, regions, and forecast sources sometimes measure waves differently. Some traditions measure from the back of the wave, which results in smaller numbers than face height. That’s why “3 feet” might mean different things to different people.

The takeaway: compare forecasts to what you actually see at the beach. Over time, you’ll learn how your favorite forecast translates to real conditions at your local spot.

Swell Period

Swell period is the time, in seconds, between one wave crest and the next passing a fixed point. It’s one of the most important — and most overlooked — numbers in a forecast.

In general:

Short period (roughly under 8 seconds): usually wind swell generated by nearby winds. Waves tend to be weaker, choppier, and less organized.
Medium period (roughly 8–12 seconds): often a mix; can produce decent surf.
Long period (roughly 12+ seconds): usually groundswell from distant storms. Waves carry more energy, arrive in more organized sets, and often break with more power.

Why it matters: A 3-foot swell at 14 seconds can produce noticeably bigger and more powerful waves at the beach than a 3-foot swell at 6 seconds. Longer-period swells carry more energy and tend to “feel” the ocean floor sooner, so they can grow more as they reach shore.

For beginners, a long-period swell can mean surprisingly powerful waves and stronger currents, even when the height number looks small. Read more in understanding tides and swell.

Swell Direction

Swell direction tells you where the swell is coming from, usually shown as a compass direction (like E, SE, or NE) or degrees.

Why it matters: every beach faces a certain direction, and some swells reach it better than others. A swell coming straight at a beach usually produces bigger surf there. A swell coming from an angle may be smaller — or may be blocked entirely by land, jetties, or other features.

Over time, you’ll learn which swell directions work best at your favorite spots. This is one of those things that’s very local.

Wind

Wind has a huge effect on wave quality — often more than wave size.

Offshore Wind

Offshore wind blows from the land toward the sea. It holds up the face of the wave, smooths it out, and generally creates clean, well-shaped waves. Light offshore wind is often ideal.

Very strong offshore winds can make it harder to paddle into waves and can blow spray off the top, but in general, offshore is good.

Onshore Wind

Onshore wind blows from the sea toward the land. It pushes the waves over, makes them crumbly and choppy, and generally creates messy conditions. Surfers often call these conditions “blown out.”

Small, gentle onshore conditions can still be fine for beginners practicing in whitewater, but the waves won’t be as clean.

Cross-Shore Wind

Cross-shore wind blows parallel to the beach. It can create bumpy conditions and may push you down the beach (and into a current) while you’re in the water.

Glassy Conditions

When there’s little or no wind, the ocean surface can look smooth and glassy. These are often some of the best and most beginner-friendly conditions.

Tip: Wind is often lighter in the early morning in many places. That’s one reason surfers love dawn patrol.

Wind Speed

Light wind (roughly under 10 mph) usually has less impact on wave quality. As wind speed increases, its effect on the waves — good or bad — becomes stronger.

Tide

Tide refers to the rise and fall of sea level, usually twice a day on the US East Coast. Forecasts typically show tide charts with high and low tide times.

Tide affects how waves break:

Some spots work best at low tide, when waves break over shallower sandbars.
Some spots work best at high tide, when there’s more water over the bottom.
Many spots are best somewhere in between, often on an incoming (rising) tide.

At some beaches, very low tide can make waves break hard and fast in shallow water. Very high tide can make waves slow and “fat,” or cause them to break right on the shore.

Every break is different. Pay attention to how the tide changes your local spot. Learn more in understanding tides and swell.

Putting It All Together

No single number tells the whole story. A good surf day comes from the combination:

Size that matches your ability
Period that produces organized waves
Direction that reaches your beach
Wind that’s light or offshore
Tide that suits your spot

A beginner-friendly day might look like: knee-to-waist-high surf, a moderate period, light or offshore wind in the morning, and a mid tide.

How to Use the WBS Surf Report

Our Surf Report is designed to help you get a quick read on conditions. When you check it:

Start with the size. Is it in a range that matches your ability?
Check the period. Short and choppy, or long and powerful?
Look at the wind. Is it light, offshore, or onshore? When does it change?
Check the tide. When are high and low? How does that fit your local spot?
Compare over time. Look at how the forecast compares to what you see at the beach.

Then go look at the ocean. The forecast is a guide; the beach is the final word. Always check local conditions, posted warnings, and lifeguard guidance before paddling out.

Keep a Simple Surf Journal

One of the best ways to learn how forecasts translate to real waves is to keep notes. After each session, jot down:

The date, time, and spot
Forecast size, period, direction, wind, and tide
What the waves actually looked like
How the session went

Over a few months, you’ll start to see patterns, and you’ll get much better at predicting when your local spots will be good.

Keep Learning

Reading forecasts is a skill you’ll keep improving for as long as you surf. For more, check out understanding tides and swell, Surfing the East Coast, and our surf lingo glossary for any terms you don’t recognize.