Governor Brown has signed AB-1014 into law. This was a reaction to the Elliot Rodger shooting four months back. Text of the law is here.
There doesn't appear to be a stipulation for appeal, nor is there a limit to how long such an order can be made to last.
DIVISION 3.2. Gun Violence Restraining Orders
CHAPTER 1. General
18100. A gun violence restraining order is an order, in writing, signed by the court, prohibiting and enjoining a named person from having in his or her custody or control, owning, purchasing, possessing, or receiving any firearms or ammunition. This division establishes a civil restraining order process to accomplish that purpose.
There doesn't appear to be a stipulation for appeal, nor is there a limit to how long such an order can be made to last.