<?php
setlocale(LC_ALL, 'pt_BR', 'pt_BR.utf-8', 'pt_BR.utf-8', 'portuguese');
date_default_timezone_set('America/Sao_Paulo');

$mes = strftime('%m');
$meses = range(--$mes, $mes+2);

foreach($meses as $item){
	echo 'valor: '. $item .' descricao: '. strftime('%B', strtotime('2015-'.$item.'-01')) .PHP_EOL;
}