Manual:$wgLocalTZoffset

Details
Set an offset from UTC in hours to use for the default timezone setting for anonymous users and new user accounts. This setting is used for most date/time displays in the software, and is overrideable in user preferences. It is *not* used for signature timestamps.

Leave at NULL to show times in universal time (UTC/GMT), or specify an offset in minutes (note that before 1.7.0 this parameter was in hours).

Changing this parameter during runtime may result in server crash (apache on windows).

1.7.0 and higher
This will change the time for MediaWiki, e.g. the time when an article was changed. During daylight saving time you need to add 60 Minutes to this parameter.

Examples: $wgLocaltimezone = 'CET'; $wgLocalTZoffset = +60;

Pre 1.7.0
You can set it to match the configured server timezone like this: $wgLocalTZoffset = date("Z") / 3600;

If your server is not configured for the timezone you want, you can set this in conjunction with the signature timezone and override the TZ environment variable like so: $wgLocaltimezone="Europe/Berlin"; putenv("TZ=$wgLocaltimezone"); $wgLocalTZoffset = date("Z") / 3600;