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Author image Bob Ernst


Geo::WeatherNWS - A simple way to get current weather data from the NWS.


  use Geo::WeatherNWS;

  my $Report=Geo::WeatherNWS::new();

  # Optionally set the server/user/directory of the reports


  # Optionally set a template file for generating HTML


  # Get the report

  $Report->getreport('kcvg');      # kcvg is the station code for
                                   # Cincinnati, OH

  $Report->getreporthttp('kcvg');  # same as before, but use the
                                   # http method to the script at
                                   # http://www.aviationweather.gov/adds/metars/
                                   # (used to be weather.noaa.gov)

  # Check for errors

  if ($Report->{error})
    print "$Report->{errortext}\n";

  # If you have the report in a string, you can now just decode it

  my $Obs="2002/02/25 12:00 NSFA 251200Z 00000KT 50KM FEW024 SCT150 27/25 Q1010";


  New for version 1.03:  the getreporthttp call now calls the script
  on the weather.noaa.gov site for those who can't FTP through

  This module is an early release of what will hopefully be a robust
  way for Perl Programmers to get current weather data from the
  National Weather Service.  Some new functions have been added since
  the 0.18 release.

  Instead of having to use the built-in server/user/password/directory
  that the module used to use, you can provide your own.  This way if
  you have access to a mirror server of the data, you can specify the
  servername, account information and directory where the files exist.
  If you don't have access to a mirror, then you don't have to specify
  anything.  The old server, etc., are still automagically selected.

  Also new in this release is that the getreport function now returns
  an error code and the FTP error message if anything goes wrong.
  Before this was added, if the server was busy or the stations text
  file was missing you couldn't tell what happened.

  Another new feature is the template system.  You can specify a file
  with the settemplatefile function.  This file is read in and all of
  the places in the file where the code sees %%name%% will be replaced
  with the proper values. An example template has been included.
  The template uses the same names as the hashref returned by the
  getreport function.

  And, same as previous releases, the getreport function retrieves
  the most current METAR formatted station report and decodes it into
  a hash that you can use.

  Some users had reported that they wanted to re-decode the raw
  observations later.  If you store the "obs" value as a string, and
  you want to re-decode it later, you can now use the decodeobs

  I thought this would be a useful module, considering that a lot of
  sites today seem to get their weather data directly through other
  sites via http. When the site you are getting your weather data
  from changes format, then you end up having to re-code your parsing
  program.  With the weather module, all you need is a four-letter
  station code to get the most recent weather observations.

  If you do not know what the station code is for your area,
  these sites might help your search:


  Since this module uses the NWS METAR Observations, you can get
  weather reports from anywhere in the world that has a four-letter
  station code.

  This module uses the Net::FTP module, so make sure it is available.

  To begin:

  use Geo::WeatherNWS;
  my $Report=Geo::WeatherNWS::new();

  If you want to change the server and user information, do it now.
  This step is not required.  If you don't call these functions, the
  module uses the defaults.


  If you want to specify a template file, use this:


  After setting the above, you can get the data.


  Now you can check to see if there was an error, and what the text
  of the error message was.

  if ($Report->{error})
    print "$Report->{errortext}";

  If you have the report in a string, you can now just decode it

  my $Obs="2002/02/25 12:00 NSFA 251200Z 00000KT 50KM FEW024 SCT150 27/25 Q1010";

  Assuming there was no error, you can now use the $Report hashref
  to display the information.  Some of the returned info is about
  the report itself, such as:

  $Report->{day}                # Report day of month
  $Report->{time}               # Report Time
  $Report->{station_type}       # Station Type (auto or manual)
  $Report->{obs}                # The Observation Text (encoded)
  $Report->{code}               # The Station Code

  These values might also be available.
  (The values {day} and {time} above should always be available.)  
  $Report->{report_date}        # Report Date
  $Report->{report_time}        # Report Time

  This is the template output:


  These are the returned values specific to the conditions:

  $Report->{conditionstext}     # Conditions text
  $Report->{conditions1}        # First Part
  $Report->{conditions2}        # Second Part

  These are the returned values specific to wind:

  $Report->{windspeedmph}       # Wind Speed (in mph)
  $Report->{windspeedkts}       # Wind Speed (in knots)
  $Report->{windspeedkmh}       # Wind Speed (in km/h)
  $Report->{winddir}            # Wind Direction (in degrees)
  $Report->{winddirtext}        # Wind Direction (text version)
  $Report->{windgustmph}        # Wind Gusts (mph)
  $Report->{windgustkts}        # Wind Gusts (knots)
  $Report->{windgustkmh}        # Wind Gusts (km/h)

  These are the returned values specific to temperature and

  $Report->{temperature_f}      # Temperature (degrees f)
  $Report->{temperature_c}      # Temperature (degrees c)
  $Report->{dewpoint_f}         # Dewpoint (degrees f)
  $Report->{dewpoint_c}         # Dewpoint (degrees c)
  $Report->{relative_humidity}  # Relative Humidity (in percent)
  $Report->{windchill_f}        # Wind Chill (degrees f)
  $Report->{windchill_c}        # Wind Chill (degrees c)
  $Report->{heat_index_f}       # Heat Index (degrees f)
  $Report->{heat_index_c}       # Heat Index (degrees c)

  Note: Due to the formulas used to get the heat index and windchill,
  sometimes these values are a little strange.  A check to see if the
  heat index is above the temperature before displaying it would be
  a good thing for you to do.  You probably don't want to display
  the windchill unless its cold either.

  These are the return values for clouds and visibility:

  $Report->{cloudcover}           # Cloudcover (text)
  $Report->{cloudlevel_arrayref}  # Arrayref holding all cloud levels
  $Report->{visibility_mi}        # Visibility (miles)
  $Report->{visibility_km}        # Visibility (kilometers)

  These are the return values for air pressure:

  $Report->{pressure_inhg}    # Air Pressure (in mercury)
  $Report->{pressure_mmhg}    # Air Pressure (in mm mercury)
  $Report->{pressure_kgcm}    # Air Pressure (kg per cm)
  $Report->{pressure_mb}      # Air Pressure (mb)
  $Report->{pressure_lbin}    # Air Pressure (psi)

  Other values MAY be returned, but only if there are remarks
  appended to the observations.  This section of the code is more
  experimental, and these names could change in future releases.

  $Report->{remark_arrayref} # Arrayref holding all remarks
  $Report->{ptemperature}     # Precise Temperature Reading
  $Report->{storm}           # Thunderstorm stats
  $Report->{slp_inhg}        # Air Pressure at Sea Level (in mercury)
  $Report->{slp_mmhg}        # Air Pressure at Sea Level (mm mercury)
  $Report->{slp_kgcm}        # Air Pressure at Sea Level (kg per cm)
  $Report->{slp_lbin}        # Air Pressure at Sea Level (psi)
  $Report->{slp_mb}          # Air Pressure at Sea Level (mb)

  Another note:  Do not be surprised if sometimes the values come
  back empty. The weather stations are not required to place all of
  the information in the reports.


new ( )

Creates an object for the NWS METAR weather report.


setservername( $Servername )

Set the server name for FTP access.

setusername( $User )

Set the username for FTP access.

setpassword( $Pass )

Set the password for FTP access.

setdirectory( $Dir )

Set the directory for the weather data on the FTP server.

settemplatefile( $Tfile )

Set the template file for the HTML report.

settimeout( $Seconds )

Set the timeout in seconds for FTP actions.

getreporthttp( $Code )

Get the METAR report for a station using HTTP.

getreport( $Station )

Get the report for a station using HTTP or FTP.

decodeobs( $Obs )

Decodeobs takes the obs in a string format and decodes them.

convert_c_to_f ( $celsius )

Convert a temperature in Celsius to Fahrenheit.

convert_f_to_c ( $fahrenheit )

Convert a temperature in Fahrenheit to Celsius.

convert_kts_to_kmh ( $knots )

Convert a speed in knots to kilometers per hour.

convert_kts_to_mph ( $knots )

Convert a speed in knots to miles per hour.

convert_miles_to_km ( $miles )

Convert a distance in miles to kilometers.

heat_index ( $fahrenheit, $rh )

Calculate the heat index based on the temperature (in Fahrenheit) and the relative humidity.

windchill ( $fahrenheit, $wind_speed_mph )

Calculate the windchill based on the temperature (in Fahrenheit) and the wind speed (in MPH).

Windchill isn't defined when the temperture is above 50 F, or for wind speeds under 4 MPH.

round ( $float )

Convert a floating point number to an integer by rounding.

translate_weather ( $coded, $old_conditionstext, $old_conditons1, $old_conditions2 )

Translate Weather into readable conditions text, per WMO Code Table 4678. This is only called internally.

decode( )

Decode does the work, and is only called internally.


  use Geo::WeatherNWS;

  my $Report=Geo::WeatherNWS::new();
  $Report->getreport('khao');        # For Hamilton, OH

  print "Temperature is $Report->{temperature_f} degrees\n";
  print "Air Pressure is $Report->{pressure_inhg} inches\n";

  # If it isn't raining, etc. - just print cloud cover

  if ($Report->{conditionstext})
      print "Conditions: $Report->{conditionstext}\n";
      print "Conditions: $Report->{cloudcover}\n";


  Marc Slagle - marc.slagle@online-rewards.com
  Bob Ernst - bobernst@cpan.org