Anticipated downtime is one hour.

Monday, December 12 at 8:00am PST the NA region servers will have some backend maintenance and updates that will impact logins to the NA shards. Downtime is expected to be an hour or less.

During the maintenance, characters currently online will be disconnected and unable to log back in to RIFT until the maintenance is cleared. New logins will also be unavailable during that time.

Watch this thread on the official forums for updates during downtime.