What is the average life expectancy of a Metar?

Similar to the above, for how long does a Metar remain valid?

Validity: Every hour, normally 5559 minutes past the hour. Data can be as old as 15 minutes, but should not be older. Valid for one hour or until the next report is released.

You might also wonder, "How often is a TAF issued?" Overview. A TAF refers to the international standard code format used for terminal forecasts that are issued to airports. TAFs can be issued four times per day at six hour intervals and last for 30 hours.

Then, you might also wonder, "How long does a TAF stay?"

24-hours

What distance does a TAF cover

TAFs are issued at minimum four times per day for major civil airports: 0000, 0600, 1200, 1800 UTC. They generally apply to 24- or 30-hour periods and an area of approximately five statute miles (8.8 km) or 5 nautical miles (9.3km) in Canada from the center an airport runway complex.