Também é correto: Eu não conduzo quando há nevoeiro/neblina.
mist should be accepted, no?
I don't think it's the case, since the only difference between mist and fog is that it's called fog when you have a short range visibility. So if you cannot drive because there is "neblina", it's definitely a fog.
Just my 2 cents.
I used the word "mist" and it was accepted. Dec.22.14
I believe ''..when it's misty'' is a correct answer too
Yeah, kind of...the meanings are definitely close enough. Just that, 'neblina' is definitely a noun, whereas, 'misty' is more of an adjective.
Depends on how strict/literal they want to be.
Considering Portuguese would hardly use an adjective form for this sentence, "when it's misty/foggy" seems to suit this one very well too.
And we would usually use the adjective in English
As both "há" and "tem" can mean "there is", are they interchangeable or are there rules for using one versus the other?
"Tem" is informal and used in spoken language.