The weather is finally getting nice out again. If you're trying to train your puppy to sleep outside, now's the time to do that. You never want to leave your puppy outside at night during the winter. However, when the weather is warm, it can be quite pleasant for your puppy to get some fresh air and sleep outside. If it's time to make the transition, your dog may need some extra coaxing, especially if it's used to being an indoor puppy, which can happen during the long winter months.