I've actually got a different set of sunglasses for every driving condition, for the convertible (firebird). I use them more for eye safety. I also wear yellow sunglasses in the crossfire for when it rains at night and red for when it rains in the day. Otherwise I wear blue during the day and none at night. The different hues take the glare off of the rain drops, since I prefer rain-X to wipers. I haven't met anyone who understands though until they try it.

You have to be careful though, because it's hard to find sunglasses that are red, yellow, or blue that let you see the world through there respective hues.