I tended to stay in my "dinner clothes" for the rest of the evening, so jeans would have been awful, since I was out on deck many times during the course of the evening.
I agree that it's downright polar some nights on the ship!
I also just find jeans a tad uncomfortable. Except maybe my old, soft, worn out jeans. But new jeans are stiff, to me.
Carnival Elation March 11
Carnival Imagination Sept 07
Carniival Sensation Dec 06
RCI Sovereign of the Seas Sept 06
Carnival Miracle Sept 05
Carnival Glory Sept 04
Carnival Fantasy Jan 04