Not sure, but consider that summer months can have little to no nighttime owing to the northerly latitude.

that's true, it does get hot sometimes in Denmark where I am, but then I open the windows when that happens.

My experience is it's either too cold to open the windows, or you will want the windows open - in my part of Denmark.

I'm not in Norway, but here in Finland I don't appreciate having nearly 30C indoors in the summer.

I don't think it was much of a problem historically, but anecdotally the summers have been getting worse* over the 15 years that I've been here. I finally had to break down and buy a portable air conditioner a few years ago.

*Some people enjoy having more hot days during the summer, of course.