They've also got a developer interface - https://developer.yr.no
One of the things that I've seen with them that I haven't seen with others is the cloud cover by layer.
https://www.yr.no/en/details/graph/2-6301678/United%20States...
https://www.yr.no/en/details/table/2-6301678/United%20States...
For doing photography (sunsets) there's a significant difference between 50% high clouds and 50% low clouds.
That L/M/H cloud breakdown is always beneficial, "Clear Outside" also has a similar feature in the forecast https://clearoutside.com/forecast/50.7/-3.52
I know that this is shameless self-promotion, but maybe this could interest you: https://sunsethue.com/ :)
I've mainly used YR:s API, it's no fuss, no registration and the data is good enough for me in a neighbouring country. It's a perk that they have some neat widget endpoints that consume a location and generate an image.