Try setting the weather to snow as I did a rally in Portugal in winter and the only time snow appeared was when the weather was showing now instead of clear.It's definitely not looking like that for me. I've had it working properly before, so I'm not quite sure what's gone wrong.
I tried changing car class to see if it was tied into that but still getting the same results. Japan is also doing the same thing for me and just looking like summer. Something's definitely not right. I'm just not sure how to fix it!