PHP Warning: date(): It is not safe - PHP Warning

I got this warning whenever my site was accessed. It is just a warning but error log is filled.I searched in the Internet and identified it can be simply rectified by changing the configurations at php.ini

[Date]
; Defines the default timezone used by the date functions
; http://php.net/date.timezone
;date.timezone =

By default it was commented and I have set to my time zone as follows

date.timezone = Asia/Colombo

The correct time zone values relevant to your location are listed here
http://www.php.net/manual/en/timezones.php

Good Reference
http://www.php.net/manual/en/timezones.php