What you're looking for is a place to put a feeding station for the colony where the property owner not only knows what you're doing and why, but will want it continued when you move on. It's important to be consistent in your feeding. Cats are very territorial. You've centered their territory around your feeding station. They'll defend their territory from encroachment by other strays and other colonies.
Cats grow a heavy winter coat, just like other winter wildlife.
In the earlier agricultural environment, there was always an outbuilding or an old vehicle they could crawl under to break the wind and to stay dry. That's the kind of shelter you're looking for or need to provide. For detailed instructions on planning and maintaining a colony, see Managing A Feral Cat Colony . This is a common occurrence from early spring through late fall. These are feral kittens.