This answer above from CtrlX is the correct answer, but it may not work completely. I added this line to my php.ini file:
date.timezone = "America/Los_Angeles"
but it did not remove the PHP error for all my files because some of my PHP scripts are in subfolders. So I had to edit .htaccess file to setup php.ini to be used recursively (in subfolders):
suphp_configpath /home/account_name/public_html
where account_name is your cpanel account name and public_html is the folder your php.ini file is in.