I stayed in Riva on Lake Garda for four days at the beginning of November a couple of years ago. We had a real mixture of weather, on two of the days it was warm and sunny, and we could sit outside, another day it was misty and the last day it poured with rain all day and was really cool. I think you will have to take a mixture of clothes . I have been to the lake previously a few times later on in November and had really mild weather but on other occasions it's been cool.
Judith