#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my @success_array = (  { hour=>22, maxDDTF=>2, ydayopen=> -53 },
                       { hour=>14, maxDDTF=>6, ydayopen=> -71 },
                       { hour=>03, maxDDTF=>1, ydayopen=> -51},
                    );
# removes hash references where hash's key of 'ydayopen' is <= -60         
@success_array = grep { $_->{ydayopen} > -60 } @success_array;

print Dumper \@success_array;  

__END__
$VAR1 = [
          {
            'hour' => 22,
            'maxDDTF' => 2,
            'ydayopen' => -53
          },
          {
            'hour' => 3,
            'maxDDTF' => 1,
            'ydayopen' => -51
          }
        ];