Something

 $select = '<select name="month" id="month" size="1">' . "\r\n";

foreach($months2 as $key => $value){
    $select .= "\t" . '<option value="' . $value . '"' .
        ($value == $month ? ' selected="selected"' : '') .
        '>' . $value. '</option>' . "\r\n" ;


}
$select .= '</select>';