The magnificent Snowy Owl
can be found almost
anywhere in the US during
the mid-winter when they tend to move south from their tundra home, and on some low-lemming years in considerable numbers. 1973/74 was remarkable for Snowies. I have a friend who had one using his roof as a perch in CT for a week.
These tundra birds are partial in general to tundra-like wind-swept areas in the winter: marshes, shores, large fields, garbage landfills, etc., and hunt from a low perch or sit on the ground. They are daytime hunters and eat any small furry things but voles (meadow mice), rats, and the like are their main diet.
In the northeast, it isn't unusual to find them on eastern Long Island and Cape Cod.
Info on the Snowy here at CLO. Remarkable the way owls can turn their heads around, isn't it, as in this photo by Janice Laurencelle via Owl Pages.