When are you going and will it be in a town? The temps shown on weather sites may not take into account the difference having buildings around makes after the sun goes down.

looking at 12th June in town

don't worry much about cold, it ought to be warmer than England (a lot more during the day) and the buildings will keep temps up at night. But you are close to the mountains so rain is possible, especially evening thunder storms. I was in Trento (just north of the lake) two weeks ago today and during the day it was tee shirt weather but they were having an unsettled spell and a bit further north there was a cold wind.

We spent a day in Desenzano last year around the 9th June. Was really nice pleasant weather during the day. Nice and warm but not too hot.

We left around 4pm though, so no idea if it was going to get cold.

I may be a bit late with this but....

got back from Lake Garda last Wednesday, stayed in Bardolino - boiling hot all week, temperatures were mid to late 20's in the day according to the weather report but I'm sure they hit the 30's some days.

Was really warm at night, couple of times I wore a cardy as it could be a bit breezy around the lake - but I do tend to be a bit nesh anyway!! Needed the air conditioning on during the day and night in the hotel.

Louise

and here is Louise's review. Thanks Louise

My pleasure.