METAR

METAR is a format for reporting weather information. METAR stands for METeorological Aerodrome Report and is predominantly used by pilots in fullfilment of a part of a pre-flight weather briefing.

It is also used by meteorologists, who use the information to help forecast the weather. METAR reports usually come from airports. Typically, reports are generated once an hour; however, if conditions change significantly, they may updated in special reports called SPECI's.

A typical METAR report contains data for the temperature, dew point, wind, precipitation, cloud cover, cloud heights, visibility, and barometric pressure. A METAR report may also contain information on precipitation amounts, lightning, and other information that would be of interest to pilots or meteorologists.

The complement to METAR reports, reporting forecasted weather rather than current weather, are TAFs. METARs and TAFs are used in VOLMET broadcasts.

United States/Canada METAR Code

This METAR example is from Trenton-Mercer Airport near Trenton, New Jersey, and was taken on December 5, 2003 at 18:53 UTC.

METAR KTTN 051853Z 04011KT 1/2SM VCTS SN FZFG BKN003 OVC010 M02/M02 A3006 RMK AO2 TSB40 SLP176 P0002 T10171017=

• METAR indicates that the following is a standard hourly observation.
• KTTN indicates the report came from Trenton-Mercer Airport, near the city of Trenton, New Jersey in the continental United States.
• 051853Z indicates the date of the month is the 5th and the time of day is 1853 Zulu time, 6:53PM Greenwich mean time, or 1:53PM Eastern Standard Time.
• 04011KT indicates the wind direction is from 40 degrees true (northeast) at a speed of 11 knots (approximately 13 statute miles per hour).
• 1/2SM indicates the prevailing visibility is 0.5 statute miles.
• VCTS indicates there is a thunderstorm in the vicinity.
• SN indicates snow is falling at a moderate intensity.
• FZFG indicates the presence of freezing fog.
• BKN003 indicates a broken cloud layer at 300 feet above ground level.
• OVC010 indicates an unbroken cloud layer (overcast) at 1,000 feet above ground level.
• M02/M02 indicates the temperature is minus 2 degrees Celsius and the dewpoint is minus 2 degrees Celsius.
• A3006 indicates the altimeter setting is 30.06 inches of mercury.
• RMK indicates the remarks section follows.
• AO2 indicates that the station has a precipitation sensor.
• TSB40 indicates the thunderstorm began 40 minutes after the top of the hour at 1840 Zulu time, 6:40PM Greenwich mean time, or 1:40PM Eastern Standard Time.
• SLP176 indicates the current barometric pressure extrapolated to sea level is 1017.6 millibars.
• P0002 indicates that 0.02 inches of liquid-equivalent precipitation accumulated during the last hour.
• T10171017 indicates the temperature is minus 1.7 degrees Celsius (29 degrees Fahrenheit) and the dewpoint is minus 1.7 degrees Celsius (29 degrees Fahrenheit).
• = indicates the end of the METAR report.

International METAR Code

US metars deviate slightly from the WMO (who write the code on behalf of ICAO) FM 15-XII code. Details listed in FAA's AIM. The following is a METAR example is from Sarafovo Airport in Burgas, Bulgaria, and was taken on February 4, 2005 at 16:00 UTC.

METAR LBBG 041600Z 12003MPS 310V290 1400 R04/P1500N R22/P1500U +SN BKN022 OVC050 M04/M07 Q1020 NOSIG 9949//91=

• METAR indicates that the following is a standard hourly observation.
• LBBG indicates the report came from Sarafovo Airport in Burgas, Bulgaria in continental Europe.
• 041600Z indicates the date of the month is the 4th and the time of day is 1600 Zulu time, 4:00PM Greenwich mean time, or 6:00PM Eastern European Time.
• 12003MPS indicates the wind direction is from 120 degrees true (east-southeast) at a speed of 3 meters per second.
• 310V290 indicates the wind direction is varying from 310 degrees true (northwest) through 120 degrees true (east-southeast) to 290 degrees true (west-northwest).
• 1400 indicates the prevailing visibility is 1400 meters.
• R04/P1500N indicates visibility along Runway 4 is 1500 meters and not changing significantly.
• R22/P1500U indicates visibility along Runway 22 is 1500 meters and rising.
• +SN indicates snow is falling at a heavy intensity.
• BKN022 indicates a broken cloud layer at 2,200 feet above ground level.
• OVC050 indicates an unbroken cloud layer (overcast) at 5,000 feet above ground level.
• M04/M07 indicates the temperature is minus 4 degrees Celsius and the dewpoint is minus 7 degrees Celsius.
• Q1020 indicates the current barometric pressure extrapolated to sea level is 1020 millibars.
• NOSIG indicates no significant change in the weather has occurred since the previous observation.
• 9949//91
• = indicates the end of the METAR report.

External links

• NOAA.gov - Information on METAR and TAF reports Also provides a link to current metar reports and cycle files.
• WMO documentation on METAR format (PDF)
• CPAN [1] Several Perl modules for parsing METAR reports are available on CPAN.
• PhpWeather is a PHP application (with a GNU GPL licence) that parses METAR reports.
• Another METAR parsing PHP script
• NOAA.gov - Complete documentation on the METAR format
• The Met Office - METARs and TAFs for the UK (requires free login)
• Nav Canada aviation weather site - provides METARs and TAFs for Canada (and some international stations)