Am I missing something? Is there no other commonly used word for elevated temperatures when speaking about the weather other than "caldo"? All I see is this word used with some sort of modifier... What about warm? What about sizzling? Am I missing something? The only other word I have encountered is afoso. The same kind of thing seems to happening on the other side of the temperature scale with "freddo". Just cold? Not chilly, or freezing or mild, etc. to imply a degree of hot or coldness?
Perhaps, it is just my (very) limited exposure to the language, so far?
I am not looking for a list of synonyms, I am looking for information about commonly used words actually used in expressions, as you would encounter if you were inside and asking someone who just came in if you needed a sweater or a heavy coat, or if it was so hot that you needed to dress in shorts and a sleeveless top. In English, we would say, "It is warm but not really hot." Or, "It is very mild outside, you do not need a sweater."