The homepage, forum, wiki and IRC will be going offline for about five minutes on 2016-12-18, between 08:00 and 08:15 UTC.
For convenience, this means:
EST (USA east coast):
2016-12-18, 03:00-03:15
UTC (UK):
2016-12-18, 08:00-08:15
AEDT (Australia east coast):
2016-12-18, 19:00-19:15
The intent is to install security updates on the server which hosts the homepage, forum, wiki and IRC. These will be non-disruptive to functionality, as the server is running a stable OS release that gets critical fixes only.