Winter around the LIS can be pretty variable first of all. Once every 20 years or so the Sound will freeze up when it gets really cold (@20*F) for two weeks and the creeks and harbors will begin to freeze up. Usually it does not freeze in my experience and in water storage is a viable option and is usually a bit cheaper then being hauled out and put on the hard.
I used a yard in Glen Cove on LI to store our 27' Tartan for 2 years and it cost less than $1K for haul out, power wash and setting up, and they allowed you to do your own bottom job. Many places do not allow that and cost much more from the outset. The yard I used has been bought up by a conglomerate and probably does not have such lax rules anymore but I will mention them: Glen Cove Marina (used to be Jude-Thaddeus).
I know of one guy on the sailnut board that took his 40' boat from Lake Champlain to a yard up the Connecticut River (I think) and perhaps there was partly an economic component to his decision. You could ask him about this. Here is a thread he sponsored while coming down the Hudson: Done with the canal... heading down the Hudson...
I doubt that City Island is very cheap but you will have to figure out the economics.