You are in PA. With cool and then cold weather approaching now, humidity (a major problem for trains and the electronics in them) should not be a problem over the cold-weather months.
As others have noted, wrap the items in a paper wrap first (ideally an acid-free paper/tissue, and definitely NOT printed paper) and then in bubble wrap. I just recently moved--actually, still in the process of doing so--but I kept and stored about 95% of the original boxes for my trains. I have done this for years to make the items far easier and safer to ship if/when I sell them. Empty boxes do take up a whole lot of space, but you will than your lucky stars you saved them if/when you move, and even when you sell them at some point.
You can buy all sorts of dehumidifying agents that you can store with your trains (sporting goods and gun stores sell a variety of types). Keeping things in plastic containers is definitely a good idea.
