use strict;
use warnings;
use DateTime;

my @dirs = ...

DIR: for my $dir (@dirs) {
    next DIR if (!($dir =~ /(\d{4})_(\d{2})_(\d{2})_(\d{2})/));
    my $dir_time = DateTime->new( year => $1,
                                  month => $2,
                                  day => $3,
                                  hour => $4, 
                                  time_zone => 'floating',
                                );
    if (0 <= DateTime->compare($dir_time, DateTime->now(time_zone => 'floating')) {
        print "whatever\n";
    }
}