METAR reports observed airport weather; TAF describes expected conditions over a defined forecast period.
The observation
A METAR is a coded aerodrome weather report. It identifies the station and observation time, then reports items such as wind, visibility, weather, cloud cover, temperature and pressure. The timestamp matters: an observation describes conditions at a moment, not the entire upcoming flight.
The forecast
A TAF sets out expected weather at an aerodrome for a stated validity period, including significant changes. It is a forecast, so crews compare it with fresh observations and other operational information rather than treating it as certainty.
What the traveller sees
Low visibility, thunderstorms or strong winds can affect arrival rates, approaches and alternate-airport choices. A departure board cannot explain the whole decision: operational limits depend on the aircraft, crew, runway and conditions along the planned route.
Why one report cannot describe the whole flight
A METAR describes observed conditions at one aerodrome at a stated time; a TAF forecasts conditions for a period there. Neither is a complete route forecast. Dispatchers and crews combine them with winds aloft, en-route hazards, alternates and updated observations. Travellers should therefore avoid reading a single airport report as a prediction that their flight will depart or arrive on time.
Questions about this topic
What does Z mean in a weather report?
Z denotes UTC. A METAR observation time and a TAF validity period are different timestamps. Convert to the airport’s local date as well as its time; midnight can change the day.
Why should I check the report time?
A weather observation describes a stated time; a forecast covers a defined validity period. Neither is an unrestricted statement about the whole journey.
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