Know a man in Florida that has a machine shop. He covers his machines with heavy blankets. Wondering if the blankets soak up some moisture and helps prevent rust? Blanks then dry out when temps go up.
I put terrycloth towels over the cast iron tables on my table saw and bandsaw. No problems with rust in an unheated shop.
I also rub them down with a new dry scotchbrite pad once a year or so and put a coat of Turtle Wax on them.