I admit I can't get my head around HTML::Parser yet, but perhaps you can cheat and use a regular expression.

while (<FH>) {
  if (m[width="14%"><font \S+ color="(.*)" \S+>(\d+)<]) {
    my ($color, $day) = ($1, $2);
    print "Day $day is $color\n";
  }
}
[download]

IMO, when the HTML you are parsing is being generated consistently, a regexp will be reliable enough and easy to adapt in the future. For safety, you can check that you found 30ish days.