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Manual Reference Pages  -  GEO::METAR (3)

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Geo::METAR - Process aviation weather reports in the METAR format.



  use Geo::METAR;
  use strict;

  my $m = new Geo::METAR;
  $m->metar("KFDY 251450Z 21012G21KT 8SM OVC065 04/M01 A3010 RMK 57014");
  print $m->dump;



METAR reports are available on-line, thanks to the National Weather Service. Since reading the METAR format isn’t easy for non-pilots, these reports are relatively useles to the common man who just wants a quick glace at the weather. This module tries to parse the METAR reports so the data can be used to create readable weather reports and/or process the data in applications.


    How you might use this

Here is how you might use the Geo::METAR module.

One use that I have had for this module is to query the NWS METAR page (using the LWP modules) at to get an up-to-date METAR. Then, I scan thru the output, looking for what looks like a METAR string (that’s not hard in Perl). Oh, EHSB can be any site location code where there is a reporting station.

I then pass the METAR into this module and get the info I want. I can then update my webcam page with the current temperature, sky conditions, or whatnot. See for yourself at

See the BUGS section for a remark about multiple passes with the same Geo::METAR object.


The following functions are defined in the METAR module. Most of them are public, meaning that you’re supposed to use them. Some are private, meaning that you’re not supposed to use them — but I won’t stop you. Assume that functions are public unless otherwise documented.
metar() metar() is the function to whwich you should pass a METAR string. It will take care of decomposing it into its component parts converting the units and so on.

Example: $m->metar("KFDY 251450Z 21012G21KT 8SM OVC065 04/M01 A3010 RMK 57014");

debug() debug() toggles debugging messages. By default, debugging is turned <B>offB>. Turn it on if you are developing METAR or having trouble with it.

debug() understands all of the folloing:

        Enable       Disable
        ------       -------
          1             0
        yes         no
        on          off

If you contact me for help, I’ll likely ask you for some debugging output.

Example: $m->debug(1);

dump() dump() will dump the internal data structure for the METAR in a semi-human readable format.

Example: $m->dump;

version() version() will print out the current version.

Example: print $m->version;

_tokenize() <B>PRIVATEB>

Called internally to break the METAR into its component tokens.

_process() <B>PRIVATEB>

Used to make sense of the tokens found in <B>B>_tokenize()<B>B>.


After you’ve called <B>B>metar()<B>B>, you’d probably like to get at the individual values for things like temperature, dew point, and so on. You do that by accessing individual variables via the METAR object.

This section lists those variables and what they represent.

If you call <B>B>dump()<B>B>, you’ll find that it spits all of these out.
VERSION The version of that you’re using.
METAR The actual, raw METAR.
TYPE Report type in English (Routine Weather Report or Special Weather Report)
SITE 4-letter site code.
DATE The date (just the day of the month) on which the report was issued.
TIME The time at which the report was issued.
MOD Modifier (AUTO/COR) if any.
WIND_DIR_ENG The current wind direction in english (Southwest, East, North, etc.)
WIND_DIR_ABB The current wind direction in abbreviated english (S, E, N, etc.)
WIND_DIR_DEG The current wind direction in degrees.
WIND_KTS The current wind speed in Knots.
WIND_MPH The current wind speed in Miles Per Hour.
WIND_GUST_KTS The current wind gusting speed in Knots.
WIND_GUST_MPH The current wind gusting speed in Miles Per Hour.
WIND_VAR The wind variation in English
WIND_VAR_1 The first wind variation direction
WIND_VAR_2 The second wind variation direction
VISIBILITY Visibility information.
WIND Wind information.
RUNWAY Runway information.
WEATHER Current weather (array)
WEATHER_LOG Current weather log (array)
SKY Current cloud cover (array)
TEMP_C Temperature in Celsius.
TEMP_F Temperature in Fahrenheit.
DEW_C Dew point in Celsius.
DEW_F Dew point in Fahrenheit.
HOURLY_TEMP_F Hourly current temperature, fahrenheit
HOURLY_TEMP_C Hourly current temperature, celcius
HOURLY_DEW_F Hourly dewpoint, fahrenheit
HOURLY_DEW_C Hourly dewpoint, celcius
ALT Altimeter setting (barometric pressure).
REMARKS Any remarks in the report.


Test suite is small and incomplete. Needs work yet.

Older versions of this module were installed as METAR instaed of Geo::METAR


The Geo::METAR is only initialized once, which means you’ll get left-over crud in variables when you call the metar() function twice.

What is an invalid METAR in one country is a standard one in the next. The standard is interpreted and used by meteorologists all over the world, with local variations. This means there will always be METARs that will trip the parser.


There is a TODO file included in the Geo::METAR distribution listing the outstanding tasks that I or others have devised. Please check that list before you submit a bug report or request a new feture. It might already be on the TODO list.


Copyright 1997-2000, Jeremy D. Zawodny <Jeremy [at]>

Copyright 2007, Koos van den Hout <>

Geo::METAR is covered under the GNU Public License (GPL) version 2 or later.

The Geo::METAR Web site is located at:


In addition to our work on Geo::METAR, We’ve received ideas, help, and patches from the following folks:

  * Ethan Dicks <ethan.dicks [at]>

    Testing of Geo::METAR at the South Pole. Corrections and pointers
        to interesting cases to test.

  * Otterboy <jong [at]>

    Random script fixes and initial debugging help

  * Remi Lefebvre <remi [at]>

    Debian packaging as libgeo-metar-perl.deb.

  * Mike Engelhart <mengelhart [at]>

    Wind direction naming corrections.

  * Michael Starling <mstarling [at]>

    Wind direction naming corrections.

  * Hans Einar Nielssen <hans.einar [at]>

    Wind direction naming corrections.

  * Nathan Neulinger <nneul [at]>

    Lots of enhancements and corrections. Too many to list here.


lcdproc at uses Geo::METAR in to display weather data on an lcd.
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