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.
CarnivalSensation February 2015
Carnival Dream November 2015
Carnival Fascination April 2014
Carnival Elation March 2011
Carnival Imagination Sept 2007
Carnival Sensation Dec 2006
RCI Sovereign of the Seas Sept 2006
Carnival Miracle Sept 2005
Carnival Glory Sept 2004
Carnival Fantasy Jan 2004