Why Wave Forecasts Are a Range, Never a Single Number
A forecast that says "3 to 5ft" isn't hedging out of caution. That range is the most honest number a real ocean forecast can actually give you.
Quick Facts
- Why a range exists
- Swell models carry real uncertainty over open-ocean distance and time
- Bigger source of error
- Local factors — wind, tide, sandbar shape — that models can't fully see in advance
- What a single number hides
- The same confidence interval, just repackaged to look more precise than it is
- How to actually use a range
- Treat the top of the range as the ceiling, not the expectation
Ocean models forecast probability, not certainty
Swell forecasting models a storm system thousands of miles away and projects how that energy travels, decays, and eventually breaks on a specific stretch of coastline days later. Every one of those steps carries real uncertainty, and that uncertainty compounds the further out the forecast reaches.
A single number just hides the same uncertainty
A forecast that confidently states "4ft" instead of "3-5ft" hasn't actually reduced the underlying uncertainty — it's just chosen not to show it to you. A wide range is a forecaster being honest about what they don't know yet.
How to actually read one
Treat the top of a stated range as what's possible under ideal local conditions, and the bottom as the realistic floor. The actual day usually lands somewhere in between, shaped by whatever wind and tide do locally that the model couldn't fully predict in advance.
A forecast that gives you one number isn't more accurate. It's just less honest about the same uncertainty.
Real conditions, not just hype
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