If you don't have a fenced in yard, or can't convince your pooch to go out there by himself, then you wear some rain gear and learn to appreciate the "joys" of weather I walk Skippy and Emilu after work in almost ANY weather - unless there is a completley severe storm, they get walked. Actually the really hot weather does us in more than cold/rainy weather.
I have a fenced yard and during the day I put on my rain coat, wait on the covered deck until he does his business and then rush out and pick it up. At night I go down with him with my rain coat on. He's a labragoat and I need to keep an eye on him.
This is exactly what I do. Mine wanted to come back in without going because they are such weenies when it comes to going outside in the rain. After a couple of times of my refusing to come back in until they went, they now go, and hurry back inside. Of course, they have to have me go with them, and then they get toweled off when we come back inside. Tails wag on that one!