One of the things that I've found on yr.no that I haven't seen on any other weather app is the classification of cloud level.

For example: https://www.yr.no/en/details/table/2-4407066/United%20States...

You will see not only the cloud cover as an overall percentage, but also the different levels. A 50 in the middle is very different than 50 in low in terms of what you can expect that day (for photographs).