Were you just using the stock widgets for the device? You should be able to long press on the home screen and add a widget!
I found out that there was an app that was somehow blocking this widget on the easy home screen. I removed the app and the widget appeared again.
The problem was happening on the easy home screen of my LG G4. I booted the device inn to safe mode and found that the clock on the widget/bar at the top of the screen would work but I could not get the weather info to appear.
I came out of safe mode and the info was there for both the weather and time but was not updating. I gave up and reset the device to factory default and so far so good
Seems that there was a piece of an app left over but I was not able to find it.