And, unfortunately, they might update those dates only in July! This is the reason why we cannot update the monthly events too far in advance as many events are only confirmed with precise dates a few weeks before.
Since it is a September event, I would venture to say it might again be the first weekend in September, as it has been in the past.
You should follow the page which has organizes the event: https://www.facebook.com/cantineneltufo.pitigliano/ to keep track if they post news about it!
Just as an FYI - this festival gets packed! and parking can be a bit confusing. So be prepared!
But it is also a great event and they have some fantastic wines. Read this article to give you an idea of some of the other great flavors that exist in this area.