What Does P6SM Mean in a TAF?
P6SM means visibility greater than 6 statute miles. P before a value means "more than". It stands for P = Plus (more than).
P6SM in a real report
TAF ... P6SM SCT040
What it changes for you
P6SM is the forecast equivalent of "good enough not to matter". It is the top
of the TAF visibility scale in the United States.
The thing worth knowing is what it is not. It is not a measurement, and it does not tell you whether the day is hazy at 7 miles or genuinely clear at 30. If that difference matters for what you are doing, the METAR will give you a measured value that the TAF never will.
The M form
The same prefix system runs the other way. M1/4SM means less than a quarter of
a statute mile, the bottom of the scale, where a more precise number would be
just as meaningless.
Related codes
Decode a report containing this code
Paste a METAR, TAF, PIREP or SIGMET into the WxDecoder decoder. Every group comes back in plain English. The raw code sits beside it, so you can check the decode rather than trust it.
Frequently asked questions
What does P6SM mean in a TAF?
Visibility greater than 6 statute miles. The P means plus. Forecasters are not asked to predict the difference between 7 and 10 miles, so the format caps good visibility at this single value.
Why do METARs give a number where TAFs give P6SM?
A METAR is an observation, so it can report a measured 10SM. A TAF is a forecast, and forecasting an exact visibility above 6 miles would be a false precision, so the format uses one value for anything better than that.