Definition of hot by Dictionary.com:
having or giving off heat; having a high temperature:
Definition of warm by Dictionary.com:
of or at a moderately high temperature; characterized by comparatively high temperature:
Many people argue that you it is wrong to say "I am (feeling) hot" and argues that "hot" refers to temperature 40℃ and above while "warm" refers to temperature 30-40℃.
I personally feel silly to say "I am (feeling) warm" because it is the fact that you have been warm all the time (unless the temperature just rose to 30℃ or dropped to 40℃).
I have tried to search about this but to no avail. Although I cannot find a direct comparison explanation ("hot" or "warm"), but I can find individually and confirm that both are grammatically correct.
Best Answer
First of all, as a speaker of American English, I would rarely say
This present progressive use of to feel is used for other things, such as
At any rate, I could say
if I wanted to report on my personal status.
But in many situations I would report on the temperature of my environment when I feel hot/warm/cold. Thus
So, yes you can say both It's hot or It's warm. And you can say this to either report a fact
or to indicate that you feel hot or warm. But feeling is subjective, and what is hot to one person may be warm to someone else.
Note I can remark on other facets of my environment, such as
but I couldn't say