Yes, they get cold. I would not leave him outdoors for any extended period of time after the temperature drops below 50 degrees. A dog house for an outdoor dog doesn't just help, it is required. Everywhere that I know of requires a dog to have adequate shelter from the elements...in my city, a dog must have a dog house with a floor that is elevated at least 4 inches off the ground. A dog house should have 2 small rooms in it...one where the dog will enter, and another off to the side of the door where he can get out of the wind. The rooms should allow the dog space to stand up, turn around, and lie down, but should not be much bigger than to allow for that, as your dog will need a smaller space to help retain heat. Flooring should be linoleum or some other surface that allows moisture to run off. Floors should never be covered with blankets...they get wet, and will actually make the dog colder. Straw is probably the best bedding, but it must be changed frequently. Be sure there is some sort of covering over the door to help block the wind...you can use a rubber flap, a piece of carpeting, or a premade dog door with a flap. Be sure the dog house is properly placed---never put the dog house in an unprotected area...I have seen so many morons put their dogs' houses in the NW corner of the yard, where it catches the coldest winds. Put the dog house next to your own house where it will have the most shelter (most likely on the south side where it will still get some sun during the day and be out of the worst of winter winds).
In my opinion, there is no excuse for getting a dog and then throwing it outside to deal with winter weather, I feel that dogs belong with their families, indoors. If you're going to keep your dog outside, though, be sure there is adequate shelter, be sure the dog has a heated water bowl, and be certain that the dog always has enough food (so he has the energy to keep warm)...dogs need much more food in winter when they live outdoors. Last, don't let your dog indoors in the daytime and then put him out to sleep at night...it's very difficult for them to adjust to the temperature extremes. Contact your local humane society for more information about caring for outside dogs...they need a LOT of extra attention in the winter.