When run in Finland (GMT +0200), the first line below prints "Jan 01
1998 00:00:00", while the second prints "Dec 31 1997 22:00:00".
<?php
echo date("M d Y H:i:s", mktime(0, 0, 0, 1, 1, 1998));
echo gmdate("M d Y H:i:s", mktime(0, 0, 0, 1, 1, 1998));
?>