That's hard for humans too. I think we need to give up on the idea that fully autonomous driving will be perfect.
I have driven in snow a few times that I was not sure I was even on the road. Or the only way I knew I was going the right direction was because I could vaguely see the break lights of the car going 15mph in front of me through snow.
That is an easy problem to solve though because I simply should not have been driving in that.