Requirements

mySQL time zones installation:

You have to follow this topic: https://dev.mysql.com/doc/refman/5.6/en/time-zone-support.html#time-zone-installation

PHP time zones installation:

Timezonedb is already integrated but may be not up-to-date. You may check that using phpinfo() function.
phpinfo() should return something like that:

date
date/time support  enabled  
"Olson" Timezone Database Version  2014.1
Timezone Database  internal  
Default timezone  Europe/Paris 

2014.1 means timezonedb version is year 2015 5th edition.

Please note that if you get the following result

0.system
It means that your PHP use the system timezone database so ensure it is up-to-date (tzdata package). The pecl/timezonedb doesn't make sense in this case.

If your PHP doesn't use the tzdata package then you may check this to update PHP timezonedb: https://pecl.php.net/package/timezonedb/

Don't forget to update your "php.ini" to enable this updated module, otherwise you'll get the old one.

and in this case, you should get something like

date

date/time support  enabled  
"Olson" Timezone Database Version  2015.5  
Timezone Database  external  
Default timezone  Europe/Paris