weather

Where in Italy?

You can see actual, day-by-day historical weather stats for major cities on timeanddate.com. I've linked to Rome's data for December 2018, but you should look at several years' data, because weather can vary a lot from year to year. Anecdotal reports from travelers who may have gone to Rome (or wherever you will be) once are not something I'd want to depend on in any way. I wouldn't expect Dec 31 to be all that similar to Dec 1, either.

I am not much of a fan of monthly averages, but they can be handy for precipitation (on average, how many days a month does it rain?) if you allow for the fact that early December and late December might be quite different. You'll find a handy climate-summary chart in the Wikipedia article for most major cities. Unfortunately, you'll see that the period on which the averages are based ends in 2000. I think we all realize that weather has changed quite a bit in the last nineteen years.

I like Wunderground website for a monthly view of temps and precipitation for historical weather data. I check every city I'll visit and look back 3-5 years. Him doesn't look like the mobile version shows precipitation. Worth using full laptop or PC for research.

There is an Italian weather app called Il Meteo that is quite detailed.

We were in Rome and Orvieto in late December 2015 2016 it was cool in the day and chilly at night.