Actually, I've been thinking about GTA having snow for quite some time.
Seeing how the next GTA will probably be much bigger, there will most likely be alot of backroads.
You go to get your mission from someone out in the hills. A massive ice and snow storm hits and the roads are either snowed shut or they are icy. You have to take a package to someone in a city and have to fight off a bunch of redneck snow plow drivers that are trying to kill you and force you off of the road.