- date_default_timezone_set: documentation ( source)
<?php
date_default_timezone_set ( 'America/Chicago' );
echo \DateTime::createFromFormat('Y-m-d H:i T', '2015-10-22 09:23 CDT')->format('c');
echo \DateTime('2015-10-22T08:50:39-0500')->format('Y-m-d H:i T');