UESP Forums

Source.

The Elder Scrolls Online undergoes regular maintenance to provide you with the best service possible. We have scheduled the following windows for this purpose, although we may not need to use them every week:

North American Megaserver
Wednesdays at 13:00 BST (8:00 a.m. EDT)
Sundays at 11:00 BST (6:00 a.m. EDT)

European Megaserver
Tuesdays at 13:00 BST (14:00 CEST)
Sundays at 09:00 BST (10:00 CEST)

Most maintenance periods will last for no more than a few hours. During these times, we'll deploy patches, server optimizations, database updates, hardware upgrades, and perform other routines that keep ESO running smoothly.

Would've been really nice if I'd seen that before I got up at six thirty to play this game...

Thanks for this, I will write this as an article.

The official maintenance times have changed (source):

North American Megaserver
Tuesdays at 8:00am EDT (12pm GMT)
Fridays at 8:00am EDT (12pm GMT)

European Megaserver
Tuesdays at 6:00am CEST (5:00am BST)
Fridays at 6:00am CEST (5:00am BST)

You can always check whether the servers are up by visiting http://forums.elderscrollsonline.com/ca ... ver-status

I have to say, these maintenance times make NO sense.

No, don't thank me for my patience zenimax. GET A SMARTER MAINTENANCE TIME!!! Why do you do scheduled maintenance during the day!? Other MMOs get this, you do not schedule maintenance when people will be trying to play. Even swtor schedules its maintenance early in the morning when the fewest people will be on. This "scheduled maintenance" that takes almost an entire day of playtime from us is WRONG. 8 AM to 1PM??? Why this time? Why not say, 3 am to 8 am like most normal mmos??? Do it in the dead of early morning. NOT half a day

No schedule is going to work for everybody.

For me, this time is great, because I need to work, and I'm on the West coast anyway so it's actually from 5 am to 10 am. But I suspect the actual answer to your question is that there are a LOT of problems for them to fix during each maintenance and they want to have as many devs around as possible to handle them. They're not just running some automated database cleanup--each time they take the server down for a long maintenance, we're getting a new patch. If they forced their development staff to be around starting at 3 am, they'd just introduce more bugs because people are sleepy, not to mention the huge hit to employee morale for a team that's probably been pushed to the breaking point before release already.

Update! Source

Starting next week Thursday, we have updated the maintenance times for the North American megaserver of The Elder Scrolls Online.
This will allow our fans in the Far East and Oceania to enjoy their Friday nights in ESO. The European maintenance windows remain unchanged.

The updated maintenance times are:

North American Megaserver
Mondays at 8:00am EDT (12pm GMT)
Thursdays at 8:00am EDT (12pm GMT)

European Megaserver
Tuesdays at 6:00am CEST (5:00am BST)
Fridays at 6:00am CEST (5:00am BST)