If you are working in multiple timezones getting the offset from a date is a little tricky because you need it in hours.
<?php
$time = new DateTime('now', new DateTimeZone('America/Los_Angeles'));
date_sunrise(
$time->getTimestamp(),
SUNFUNCS_RET_TIMESTAMP,
38.4,
-9,
90,
$time->getOffset() / 3600
);