rain   sunny   dry-cloudy
rain         0.6    0.2      0.2
sunny        0.3    0.5      0.2
dry-cloudy   0.4    0.3      0.3

##</code><code>##

$ ./2.icons.pl 
{
  "\@context" => [],
  "icons" => {
    bkn             => { description => "Mostly cloudy" },
    blizzard        => { description => "Blizzard" },
    cold            => { description => "Cold" },
    dust            => { description => "Dust" },
    few             => { description => "A few clouds" },
    fog             => { description => "Fog/mist" },
    fzra            => { description => "Freezing rain" },
    haze            => { description => "Haze" },
    hot             => { description => "Hot" },
    hurricane       => { description => "Hurricane conditions" },
    ovc             => { description => "Overcast" },
    rain            => { description => "Rain" },
    rain_fzra       => { description => "Rain/freezing rain" },
    rain_showers    => { description => "Rain showers (high cloud cover)" },
    rain_showers_hi => { description => "Rain showers (low cloud cover)" },
    rain_sleet      => { description => "Rain/sleet" },
    rain_snow       => { description => "Rain/snow" },
    sct             => { description => "Partly cloudy" },
    skc             => { description => "Fair/clear" },
    sleet           => { description => "Sleet" },
    smoke           => { description => "Smoke" },
    snow            => { description => "Snow" },
    snow_fzra       => { description => "Freezing rain/snow" },
    snow_sleet      => { description => "Rain/sleet" },
    tornado         => { description => "Tornado" },
    tropical_storm  => { description => "Tropical storm conditions" },
    tsra            => { description => "Thunderstorm (high cloud cover)" },
    tsra_hi         => { description => "Thunderstorm (low cloud cover)" },
    tsra_sct        => { description => "Thunderstorm (medium cloud cover)" },
    wind_bkn        => { description => "Mostly cloudy and windy" },
    wind_few        => { description => "A few clouds and windy" },
    wind_ovc        => { description => "Overcast and windy" },
    wind_sct        => { description => "Partly cloudy and windy" },
    wind_skc        => { description => "Fair/clear and windy" },
  },
}
========================
Stochastic Matrix with side: 
hurricane
rain_showers_hi
few
fzra
rain_snow
bkn
snow_fzra
snow
snow_sleet
wind_ovc
blizzard
cold
smoke
tropical_storm
skc
haze
wind_few
sct
rain
sleet
ovc
tsra
tornado
tsra_sct
hot
fog
wind_bkn
rain_fzra
dust
wind_sct
tsra_hi
rain_showers
rain_sleet
wind_skc
========================
URL = https://api.weather.gov/icons/land/day/tsra_sct,20/tsra_sct,40?size=medium
   tsra_sct => 'Thunderstorm (medium cloud cover)'

URL = https://api.weather.gov/icons/land/day/rain_showers,30/tsra_hi,30?size=medium
   tsra_hi => 'Thunderstorm (low cloud cover)'

URL = https://api.weather.gov/icons/land/night/rain_showers,30/rain_showers?size=medium
   rain_showers => 'Rain showers (high cloud cover)'

URL = https://api.weather.gov/icons/land/day/bkn?size=medium
   bkn => 'Mostly cloudy'

$ cat 2.icons.pl 
#!/usr/bin/perl -w

use strict;
use LWP::UserAgent;
use Data::Dump;
use JSON::Parse 'parse_json';
use 5.016;

my $ua = LWP::UserAgent->new( 'send_te' => '0' );
my $r  = HTTP::Request->new(
  'GET' => 'https://api.weather.gov/icons',
  [
    'Cache-Control' => 'max-age=0',
    'Connection'    => 'keep-alive',
    'Accept' =>
'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
    'Accept-Encoding' => 'gzip, x-gzip, deflate, x-bzip2, bzip2',
    'Accept-Language' => 'en-US,en;q=0.5',
    'Host'            => 'api.weather.gov:443',
    'User-Agent' =>
'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:74.0) Gecko/20100101 Firefox/74.0',
    'Upgrade-Insecure-Requests' => '1',
  ],

);

my $out;
my $res = $ua->request( $r, );
if ( $res->is_success ) {
  my $json = $res->decoded_content;
  $out = parse_json $json;
}
else {
  print "Error: " . $res->status_line . "\n";
}

dd $out;

my %xlated_abbrev;    #simple abbreviation table => description

foreach my $key ( keys %{ $out->{icons} } )    #gen simple xlate table
{
  $xlated_abbrev{$key} = $out->{icons}{$key}{description};
}

my @keys2 = keys %xlated_abbrev;
say "========================";
say "Stochastic Matrix with side: ";
for (@keys2){
say "$_";
};
say "========================";
my @urls = (
  'https://api.weather.gov/icons/land/day/tsra_sct,20/tsra_sct,40?size=medium',
  'https://api.weather.gov/icons/land/day/rain_showers,30/tsra_hi,30?size=medium',
  'https://api.weather.gov/icons/land/night/rain_showers,30/rain_showers?size=medium',
  'https://api.weather.gov/icons/land/day/bkn?size=medium'
);

foreach my $url (@urls) {
  my $last_path = ( split( '/', $url ) )[-1];
  my ($abbrev_to_xlate) = $last_path =~ /^(\w+)/;

  print "URL = $url\n";
  print "   $abbrev_to_xlate => \'$xlated_abbrev{$abbrev_to_xlate}\'\n\n";
}

__END__

Created from curl command line
curl 'https://api.weather.gov/icons' -H 'User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:74.0) Gecko/20100101 Firefox/74.0' -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8' -H 'Accept-Language: en-US,en;q=0.5' --compressed -H 'Connection: keep-alive' -H 'Upgrade-Insecure-Requests: 1' -H 'Cache-Control: max-age=0'


$