The weather forecast for Rome
In Rome the first real cold of the season will come, Wednesday: the weather will be clear but the minimum will be 5 degrees, while the maximum will be around 11 degrees.
The weather forecast for Milan
In Milan, in the meantime, it will be even colder than usual: minimum at 1 degree and maximum at 5. However, it will be nice all day, except for a few fogboards in the morning and evening.
The maps and forecasts come from the site of the Italian Air Force, what you have to visit if you want reliable forecasts (and slightly updated compared to those in this article) and stay away from unnecessary alarmism.