In Milano, Venice or Lake Como area the temperature will be cold but not unpleasant, about in the 50's F. The most annoying thing will be the humidity, sometimes the fog too: in a cloudy and foggy day Venice can really be unpleasant, even if it looks oddly interesting. In southern places like Rome you just need a little sun to change a November day into almost summer, but anyway temperatures are milder. Rain can be on the way at any time in the north, so you'll need some rain gear. We have a sort of indian summer too, called St.Martin's summer, at mid November, but it can mean anything from a sunny and warm week to a couple of brighter days.

Have a nice trip, Paolo