Beginning at 4:00 am Pacific time Monday October 11th, we will be performing software maintenance on the Steam servers. We expect the resulting downtime to last four hours at most, putting the end of the window at 8:00 am Pacific time.

Some Steam services will be offline during this time. Affected services will include the Steam Community, in-game matchmaking or lobbies, downloading games from Steam content servers, and making purchases from the Steam store. Games that do not rely on Steam matchmaking services should remain playable.

We will work to make this downtime as short as possible. Thank you for your patience!
Source Beginning at 4:00 am Pacific time Monday October 11th, we will be performing software maintenance on the Steam servers. We expect the resulting downtime to last four hours at most, putting the end of the window at 8:00 am Pacific time.

Some Steam services will be offline during this time. Affected services will include the Steam Community, in-game matchmaking or lobbies, downloading games from Steam content servers, and making purchases from the Steam store. Games that do not rely on Steam matchmaking services should remain playable.

We will work to make this downtime as short as possible. Thank you for your patience!
Source