Blizzard announced a new Maintenance Schedule that will allow less downtime:

Drysc: Every Tuesday all realms are brought down for scheduled weekly maintenance. This maintenance window is used to perform tasks on the realm databases and hardware, and to take care of any other tasks that would not normally be possible while the realms are live. In the past few months, however, we have been intermittently testing the ability to perform these maintenance tasks while the realms are still up and available to players.

Based on the positive results of these tests, we’re happy to announce that we’ll be switching to a new maintenance schedule that will only require us to bring down realms for maintenance every other week. On the weeks in which we don’t take the realms down for maintenance, we’ll only be issuing rolling restarts, allowing play to continue with only a very brief interruption.

An exception to this schedule will be for the release of patches that require realm downtime during weeks in which maintenance would not normally be scheduled. In such cases, the schedule will start over, with the following week being maintenance-free instead. This allows us to release a patch without having three straight weeks of maintenance downtime. Here’s an example of how the maintenance schedule will look, factoring in all of the above:

Week 1: Rolling restarts

Week 2: Maintenance

Week 3: Patch and maintenance

Week 4: Rolling restarts

Week 5: Maintenance

Week 6: Rolling restarts

The new schedule takes effect immediately, starting with rolling restarts this Tuesday instead of full maintenance downtime. As previously, the schedule for the rolling restarts or full maintenance will be posted in the news window viewable at the game’s login screen, and a 15-minute countdown timer will appear on each realm prior to its scheduled restart or downtime.