Surf Report vs Surf Forecast: What's the Difference?

A surf forecast is a prediction of what the ocean will do, generated by a computer model from weather and buoy data. A surf report is a description of what the ocean is actually doing right now, made by a person or camera at the beach. Forecasts look forward and are modeled; reports describe the present and are observed. Most surfers use both, and the gap between them is where a wasted drive usually happens.

What is a surf forecast?

A forecast starts with global weather models. Storms far out at sea generate swell, and models project how that swell will travel, how big it will be when it arrives, and when it will land. Layer in predicted wind and published tide tables, and you get the familiar forecast grid: wave height, swell period, swell direction, wind, and tide, hour by hour for the coming days.

Forecasts are genuinely good at the large-scale physics. Swell takes days to cross an ocean, and its size, period, and direction are governed by well-understood behavior. A forecast telling you a long-period swell arrives Thursday is usually right about that.

What is a surf report?

A report is an observation. Someone looks at the water — in person, or through a beach cam — and describes it: how big it's actually breaking, whether the wind has come up, whether it's clean or blown out, how many people are on it. A report can't tell you about Thursday. It tells you about right now, which is the only thing that matters if you're deciding whether to get in the car.

• Forecast: modeled, predictive, covers days ahead, describes swell arriving at the coast.
• Report: observed, current, covers this moment, describes what the wave is doing at one specific break.

Why does the forecast so often not match the beach?

Because a forecast models the ocean offshore, and you surf the last hundred metres of it. Several things change the wave between the buoy and the sand:

• Local wind. A few knots of onshore breeze can turn a clean forecast into unsurfable chop, and wind is the least reliable part of any forecast.
• Bathymetry. Sandbars move. A beach break that barrelled last month can be a closeout this month on identical numbers.
• Tide interaction. The same swell can be perfect at mid tide and unrideable at high, and how a spot responds is local knowledge no model holds.
• Swell window. A big reading at the buoy means nothing if the swell direction can't physically reach your spot.
• Crowd. No forecast models the twenty people who read the same forecast you did.

This is why two spots ten minutes apart, on the exact same forecast, can be completely different surfs.

Which should you actually use?

Use them for different jobs. Use the forecast to plan — to decide which morning this week is worth setting an alarm for. Use a live report to commit — to confirm, in the twenty minutes before you leave, that the window is actually on and the wind hasn't ruined it.

The failure mode almost every surfer knows is planning and committing off the same forecast: the numbers looked great last night, so you drove forty minutes at dawn to find it onshore and closing out.

The short version

A forecast tells you when it might be good. A report tells you if it is good. Check the forecast the night before, check a report before you leave, and you'll stop making the drive for nothing.