Can someone tell me wha the weather will be like in Rome and the eastern part of Italy, the Le Marche region in late November to early December?
I cannot comment on the eastern part of Italy. However, I was in Rome in mid-December 2017 & 2018. The temperatures were chilly in the morning (maybe early 40s) but a pleasant mid 50s by the afternoon.
Even the meteorologists can't do that at this point. The website timeanddate.com has actual, historical, day-by-day weather statistics going back at least ten years. Pick a city or two in the area and look at November and December 2018, 2017, 2016, etc. I've linked to Ancona's data for November 2018. That information should give you a decent idea of the range of weather you might experience.