Updated June 5th, 2019.
Apple has a web page showing the status of iCloud services such as iCloud Backups, iCloud Contacts synching, iCloud Calendar synching, and so on. If something “cloudy” isn’t working for you, maybe it’s not you! Maybe iCloud is down. See the current iCloud services status by clicking here.
Bonus: you’ll see a lot more than iCloud status on that page.
You’ll also see the status of various iTunes services (iTunes Match, the iTunes Store, iTunes in the Cloud, Apple Music), and the status of the Mac App Store, and the status of FaceTime, Find My Friends, and many, many more. Apple historically has a great track record of keeping their services running, but every so often something goes down. If you’re having problems with something that needs to tap into one of Apple’s services, click the link to see the Apple Services Status page. You won’t know until you click.