Every dog responds differently to different climatic conditions. Some dogs, can handle the cold weather, like Northern breeds while small dogs with little hair cannot handle extreme cold or hot weather. So, they should not be made to stay outside during extreme weather conditions.
The area of the dog house should be large enough so that the dog can feel comfortable to stand, turn around and lay down. But the dog house should not be so large that the dog does not feel secured with the closeness of the four walls. Even in the winters, a dog can warm up the house with his own body heat. One can also fix up the insulation inside the dog house, and believe me that it is not as difficult as it seems to be. This insulation can help to keep your dog warm in the winter and cool in the summer.