Though a typical METAR consists of a mixture of numbers, symbols, and letters all jumbled together, they’re not too difficult to understand, especially if you know what each section means!
METAR reports are usually created either by airports or weather observation stations and follow automated programming that ensures each METAR report consists of the same sequence, which is as follows:
- Section one - METAR report type: This section signifies what type of METAR report it is, and consists of four letters.
- Section two - The station identification: This section indicates what part of the world it comes from, and consists of four letters.
- Section three - Date and time: This section contains information on the time and date it was generated, and consists of six letters.
- Section four - Modifier: This section will let you know whether or not the report has been generated automatically. If it does, it will state ‘AUTO’.
- Section five - Wind and visibility: This section reports wind speeds and prevailing visibility, with the wind being reported in 5 numbers (sometimes 6 if speeds are high) with visibility being reported in a four-code sequence.
- Section six - Weather: Like the section name suggests, in this part of the report you’ll find information about the weather. Here you will find information on the intensity of the weather, as well as if there are any dangerous weather conditions within a 10-mile vicinity of the airport.
- Section seven - Sky condition: This section will report the cloud conditions in the sky, and contains information about the types of clouds, as well as how high they are.
- Section eight - Temperature/Altimeter: The temperature is reported here, and will always be listed in whole degrees celsius. Sometimes, information about the altimeter may also be displayed here.
How do I decode a Metar report?
METAR reports always contain the following information in the same sequence, which is important to know, especially if you want to decode the METAR report. Let’s take a closer look at what each section means:
- METAR report type - The first part of the METAR report will alert you to whether or not it is a routine METAR report that is transmitted every hour, or whether it is a special type of report known as a SPECI, which are only ever sent when critical information needs to be disclosed - such as aircraft malfunctions or rapidly changing weather. Therefore, the beginning of a METAR report will always start with either METAR or SPECI.
- The station identification - The next part of a METAR report will feature a four-letter code established by the International Civil Aviation Organization. Across most states of America, a unique three-letter code will be preceded by the letter ‘K’. However, in other areas of the world, including both Hawaii and Alaska, the identification is different and begins by identifying the region or state in the first two letters of the four-letter code. As an example, Hawaii always starts with ‘PH.’
- Date and time - The next part of the METAR report will contain a 6-digit group that indicates the date and time it was created. The first two digits are always the date, and the last four digits are always the time of the METAR.
- Modifier - This next section will tell you whether the METAR has come from an automated source, as well as if any corrections have been made. If it reads, ‘AUTO’ then it has come from an automated source, while ‘COR’ will indicate if any corrections have been made.
- Wind and visibility - The first part of this section indicates wind speeds and is usually reported in 5 numbers. However, if speed is greater than 99 knots, it is reported in 6 numbers. As for visibility, this is reported via statute miles indicated by two numbers followed by the letter sequence ‘SM’. For example, if it read: ½ SM, then it would mean prevailing visibility can be expected for the next half of a mile.
- Weather - In this section, weather intensity is reported as either light (-), moderate ( ), or heavy (+). If sudden weather conditions change and are in the vicinity of the airport (10-mile radius), these will be reported as ‘VC.’ Additionally, you may also see ‘TS’ which indicates thunderstorms, or ‘RA’ which indicates rain.
- Sky condition - This section provides information about cloud cover. The height of the cloud is reported in a three-digit number, while letter codes are used to indicate the type of cloud. For example, ‘BKN007’ would stand for broken clouds at 700 feet.
- Temperature/Altimeter - This section shows the temperature, which will be described in whole degrees celsius. This section may also show the altimeter.
How is Metar generated?
METAR reports are typically generated from weather observation stations or airports. More often than not, though, META reports are usually generated from an automated observation system.
They are usually generated once every hour, although some stations can generate them at an even quicker rate of once every half hour.
In the USA, the FAA is able to poll all systems remotely and then spread all of the generated reports via METAR format. Though it’s generally unclear whether METAR reports are generated via radio or mobile, weather stations have a vast range of operators and capabilities.
Therefore, while it is possible that individual workers may very well look over the reports before they are transmitted, it is to make sure that there are no mistakes, it is much more common for the vast majority of all METAR reports to be both generated automatically and distributed automatically.
What does a Metar stand for?
METAR originates from airports and permanent weather observation stations and stands for Meteorological Terminal Aviation Routine Weather Report.
However, in the United States, the FAA (federal aviation administration) uses a slightly different term and describes the METAR report as standing for Aviation Weather Report.
As a side note, it’s worth noting that both the United Kingdom’s Met Office and the National Oceanic and Atmospheric Administration both use the FAA's version of METAR, although the structure and purpose are the exact same as a METAR report - the only difference is the name.
Additionally, METAR is also sometimes referred to as Meteorigical Terminal Aviation Routine Weather Report or Meteorological Aerodrome Report.
How do you read wind forecast aviation?
Besides METAR, there are other ways that pilots are able to gain information on incoming weather conditions, and one of the most common ways is via a dedicated wind forecast.
An aviation wind forecast, sometimes also known as a winds aloft forecast, is a type of forecast that reports wind conditions at certain altitudes. This type of forecast is specifically used for aviation purposes, and can sometimes include information about the temperature, too.
In these types of forecasts, the easiest way to begin reading them is by first understanding what the different components of the forecast mean. Focusing on the wind conditions, the wind direction within this type of forecast will be displayed as ‘DD’ while the wind speed will be displayed as ‘SS’.
In a report, both of these components are displayed in a simple 4-digit number sequence (eg. 3287) indicating that the wind direction is 320 degrees north, and the wind speed is 87 knots. Keep in mind that the wind direction is always rounded up to the nearest 10 degrees and that the trailing zero is almost always excluded.