My yorkies are kept in the house. They are too sensitive to the environment. Plus it is easier to keep them clean and tangle free. I know of a breeder that keeps her yorkies outside and she will let you know that they are her money makers and their condition shows just that. They really are in sad shape.
Yorkies are people dogs and prefer to be around their people. If you keep one outside, you would not be giving them the adequate attention they need. Not to mention, all of the critters out there that could bite/sting them.
