The Street Fighter V servers are going down for maintenance. This server maintenance will last for a total of five hours, and will take place from 2-7pm PST. That’s from 5pm to 10pm for east coasters.
Capcom announced the information on the official Street Fighter V server Twitter account:

We will perform server maintenance from 2pm to 7pm on 11/28 PST. Thank you for your patience and support.
— SFV Server (@SFVServer) November 27, 2017

The reason for the Street Fighter V server maintenance" Capcom is taking time to implement the new premium costumes that were recently announced. There are two different different types of costumes: Holiday and Nostalgia. Learn more about them below:
The Holiday costumes, which you can find in the gallery, give Kolin, Alex, Menat, Cammy, Chun-Li, Karin, Balrog, and Birdie new costumes on November 29. There are 10 new costumes in total, and along with the new batch of outfits, last year?s Holiday costumes for Juri, Laura, Zangief, Karin, Ken, R. Mika, and the Frosty Boulevard Stage will be available for purchase again as part of the 2016 Holiday Pack. The pack will be 50% off as a special thank you to the fighters around the world. The Nostalgia and Combat costumes ? also found in the gallery above ? also gives fighters a blast to the past in the form of older costumes. Karin, Birdie, Balrog, and Chun-Li all get older costumes in the Nostalgia department, and  Chun-Li also gets another police-themed outfit to battle in...