Ive raised hogs for over 12 years and they can withstand some mighty cold temps. As with most animals it is not the cold that harms them, it could be 20 below zero and they will befine , IF they are protected from the WIND, AND WET.
As long as they stay dry and protected from the wind nearly all animals will be fine. My hunting hounds live outside year round in dog houses with straw, thats another thing they need lots of bedding to burrow into. My cattle go into the woods when it gets real cold and burrow down into leaves and even under cedar trees.
What does bother me about your neighborhood pig, and will explain why he keeps breaking loose is the fact that pigs are not solitary animals. When I raise pigs I always have a minimum of 2. Mentaly pigs can not stand being alone. Also do to their sparse hair, in cold weather they nest together for comfort, nesting is burrowing into bedding. And if this pig is alone that is the crime.
hope Ive been some help
josh

Yes, I feel better now thanks. This was the first time I noticed him outside in that shelter, so I'm betting that he gets put inside at night. I wonder if the horses that board there are is "herd"? I hope so. Never knew that pigs were that social.

Other animals can be herd mates, but horses are snobby, as are cattle, in that if they have others of their own kind , they ignore everyone else. Thats why when you use animals like donkeys or lamas as guardian animals they tell you to only have one, otherwise they will not bond with the sheep or goats.
josh