I had a problem somewhat similiar with my dog Nikka, she's completely housebroken, but when it rains she hates going out. She'll run out to pee on the deck not in the yard, but won't poop, so I come home to it in the house. I ended up walking out with her when it rained (painful since I had to get an unbrella and stand there), but wouldn't let her come in until I saw her move off the deck into the yard to do her business. If she came up before she pooped I confined her to a small area in the kitchen(about crate size), so that if she went it would be like she was going in her sleeping area and she's way to much of a priss to ever do that. It seemed to work, now she'll run down do her business really quickly and run back up.