One of the most famous sunrise spots in Venice is the Accademia bridge. In early August, you have to be there before 6 am, fighting for a place on the bridge and suffering 27 degrees with high humidity. But I don't care if this is the result you get!
Venice is an awesome city, regardless what kind of weather you experience, you can always do some magic photos. This morning though I got surprised with a beautiful sunrise after I spent an hour on St. Mark's Square during blue hour. This sunrise looks warm, but in fact I experienced about 4 degrees and it was freezingly cold, especially as I was only standing around.