"The shower is very warm."
Translation:Dușul este foarte cald.
In that case, I think that perhaps the two words are used differently in the two languages, for often when I see "cald" in this course, I think that in English we'd say "hot". We don't often talk in English of "warm" showers, let alone would say that a shower was "very warm". We generally want our showers to be "hot".
Here's a couple of other examples, from Duo's dictionary:
Mâncăm un cartof cald și proaspăt.
"We eat a warm and fresh potato."
Noi mâncăm supă caldă la prânz.
"We eat warm soup for lunch."
With food too, we usually prefer it to be "hot". If I got potatoes or soup in a restaurant and they were merely what we call "warm", I'd send them back. :)
And It seems that *fierbinte" is more "extremely hot, scorching, boiling"