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I was wondering how long is the METAR report valid for after issuance? I know some airports issue them every 30 minutes and some every hour. So I wanted to know if a METAR is issued at 8:30AM then will it be valid till next Metar report i.e. 9:00AM or is it just valid for 10-15 minutes after that ?

Pondlife
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Avgeeker
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  • What does "valid" mean in this context? It's an historical report of what the weather was at the time of issue. Metar reports are typically issued at about :53 past each hour, and also when conditions change "enough" to require one (i.e. a change from 8,000 SCT to 6,000 SCT might not warrant a new one, while 2,000 SCT to 1,000 BKN probably would). But the old one isn't invalidated; it's still out there to reference for trend information: it's just no longer the most recent one. – Ralph J Mar 07 '21 at 15:50
  • About one minute, practically speaking. I've found then useful only when aggregated with METARS from other areas at about the same time -or- for identifying a trend over a few hours. The question they answer is: "what can I generally expect to see at this airport when I arrive in about an hour or two?" Big weather events throw that out the window though. – acpilot Mar 07 '21 at 16:28
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    Typically they are "valid until the next one is issued". Large weather events may mean that there is a METAR issued between regularly scheduled ones. METAR's are really only valid for flight planning purposes, once you are in the air you should rely on ATIS, NEXRAD, and other in-flight services. – Ron Beyer Mar 07 '21 at 17:01
  • Thanks for your answers ! – Avgeeker Mar 07 '21 at 17:13
  • Related – Pondlife Mar 08 '21 at 00:31

1 Answers1

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A METAR is a report of conditions at a specific time, so it's only valid when it's issued. It's not a forecast, the weather could be different 5 minutes later. TAFs are forecasts that have a time range, they are valid during that time range. That doesn't mean they are guaranteed to be correct, it's just a prediction.

GdD
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  • This is correct. Metars are typically issued once an hour at the 55 minute mark. The metar can be issued more frequently is weather changes from the previous metar or if a correction is made to a previous metar. – wbeard52 Mar 07 '21 at 19:59