Understanding METAR and TAF Reports

METAR and TAF are two of the most widely used aviation weather products in the world. Both follow a standardised international format, which means that once you understand the structure, you can read a report from almost any airport, regardless of where you are.

What is a METAR

METAR stands for Meteorological Aerodrome Report. It is a snapshot of actual weather conditions at an aerodrome, issued at fixed intervals, typically every half hour or hour, with special reports issued if conditions change significantly between those times. A METAR describes what is happening right now, or very recently, rather than what is expected to happen.

A typical METAR includes the following elements, usually in this order:

The aerodrome identifier, a four letter code unique to that airport.
The date and time of the observation, given in coordinated universal time.
Wind direction and speed, including gusts if present.
Visibility, usually given in metres or kilometres.
Present weather, such as rain, drizzle, fog or thunderstorms, described with standard abbreviations.
Cloud layers, including the type of cloud and the height of its base above the aerodrome.
Temperature and dew point.
Atmospheric pressure, usually given as the altimeter setting.
Additional remarks, where relevant, such as recent weather or trend information.

What is a TAF

TAF stands for Terminal Aerodrome Forecast. Unlike a METAR, which reports current conditions, a TAF predicts expected weather at a specific aerodrome over a set period, commonly covering the next nine to thirty hours depending on the issuing authority. TAFs are updated at regular intervals and amended if conditions change significantly from what was originally forecast.

A TAF uses many of the same elements as a METAR, such as wind, visibility, weather and cloud, but arranges them to show how conditions are expected to change over time. It may include several time periods within a single forecast, each describing a different expected combination of wind, visibility and cloud. Terms such as temporary changes, probability of certain conditions, and becoming or gradually changing conditions are used to express how confident the forecaster is and how conditions might evolve.

Why the format matters

The compact, coded format of METAR and TAF reports exists for practical reasons. Pilots and air traffic controllers need to absorb a large amount of information quickly, often while managing other tasks. A standardised, abbreviated format allows this information to be transmitted efficiently and understood consistently across different countries and languages. It also makes the reports easy to process by computer systems used in flight planning and briefing tools.

Reading a report step by step

When learning to read a METAR or TAF, it helps to work through it piece by piece rather than trying to absorb it all at once. Start by identifying the aerodrome and the time of the report. Then look at wind, since this affects runway choice and crosswind components. Move on to visibility and any present weather, which determine whether visual flight is possible. Finally, check cloud base and temperature and dew point, which together can indicate the likelihood of low cloud or fog forming.

With practice, this sequence becomes quick and automatic, allowing a pilot to extract the key safety relevant information from a report within seconds.

Limitations to keep in mind

A METAR only describes conditions at the moment it was issued, and conditions can change quickly, particularly around thunderstorms or frontal systems. A TAF is a forecast, not a guarantee, and actual conditions can differ from what was predicted, especially further into the forecast period. For these reasons, both report types are normally used together with other sources of information, such as area forecasts, charts and, where available, more recent observations, rather than relied upon in isolation.