my @envars;

push @envars,{ value => 23, description => 'temperature in Celsius' },
              { value => 56, description => 'relative humidity in %' },
              { value => 1008.1, description => 'pressure in millibars' },
              { value => 4, description => 'dewpoint in degrees Celsius' },
              { value => 344, description => 'total column ozone in Dobson Units' };

##</code><code>##

# say you've got 2 parallel arrays @values and @descriptions
my @envars = map({ value => $values[$_], description => $descriptions[$_] }, 0..$#values);

##</code><code>##

# Same assumption as before ...
for my $i (0..$#values) {
  push @envars, { value => $values[$i], description => $descriptions[$i] };
}