I think "il fait mauvais" is short for "il fait mauvais temps".

Merci Alan.

I know what the sentence means thanks, but my question was: is the word "mauvais" being used as an adverb or an adjective? - However, since asking this question, I have found out that the word "mauvais" is an adverb when used with the verb faire: fais/faisait, when saying that the weather is bad. It's one of two times that mauvais is an adverb. It is usually an adjective. If what I have written here is incorrect, would someone please let me know?

Kind Regards to all,

Cheryl

Perhaps I wasn't clear enough. I was suggesting (I may be wrong) that "mauvais" is an adjective modifying "temps", even when the word is omitted from the sentence.

Hi Alan,

Thanks for your reply. I understand your first reply now thanks, and yes, mauvais does indeed seem to be an adjective describing bad weather. Some reliable websites that I later read though, inform that there are two occasions when mauvais works as an adverb. One is when talking about the weather: il fais mauvais. The other time is with the verb se sentir, to feel bad: elle se sent mauvais; not: elle se sent mal.

Cheryl