When iCloud sign in problems start it will impact many Apple services, as seen on their own status page with alerts being sent out. Apple products and services supported by iCloud include the iPhone, iPad, iPods, iCloud Drive, Apple Documents, passwords and Keychain, iMovie Theater, Photos, and even iWork for the cloud.
There’s hundreds of millions of users between Mac and iOS, so if there ends up being a global outage then iCloud going down today will hit millions all at the same time. This isn’t always the case, as in most circumstances problems are felt in certain regions, so iCloud could go down in the United States but not UK, etc.
Is iCloud down for you on Saturday December 7, 2019? If so, what services do you have sign in problems with and on what devices? You will see status updates from other Apple users and can also help others with their problems, so if there’s many reports you know something is down. We will also offer official updates when Apple releases details.
Update May 21: Apple’s status page mentions iCloud is down today along with many services that rely on it. This includes Find My iPhone not working on iOS devices.