A GTA Online glitch reveals the snowy streets of North Yankton can be found in the online component of Grand Theft Auto 5, suggesting the area may feature (officially) in some future update. North Yankton, if you recall, is the state in which the very first mission takes place, set some nine years before the main events of the game. If you fancy revisiting the area in GTA Online, this CVG video shows you how to get there.
To summarize, you'll have to replay that prologue mission, then get to a certain point and stand in a certain place, then get a friend to invite you into a GTA Online closed session. After that you'll have to call a helicopter, and head to some mountains floating surreally in the bottom right of the map. Simple, no? Well no, no it's not, but it is a bit clever.
Anyway, get your snow boots on while you still can, because it seems likely Rockstar will shut off the route in a future patch.