date - PHP set default time zone is not accurate -

i on east coast. when google time in denver , compare output timezone change:

$sitesettings = new sitesettings(); $settings = $sitesettings->getsettings();  date_default_timezone_set($settings["data"]["timezone"]);  echo date_default_timezone_get(), '--', date("y-m-d g:i:a"),'<br />'; 

the time 1 hour off timezone database america/denver. because php date functions not accurate, or because google , php date point different timezones?

i have hard coded america/denver default timezone , working fine, example:

<?php date_default_timezone_set('america/denver'); echo date_default_timezone_get(), '--', date("y-m-d g:i:a"),'<br />'; ?> 

codepad output

google result