Re: vineyards and ice fairs
A few years ago I was in Slovakia, in temperatures of -20C with snow on the ground. They said it was a normal winter.
They have vinyards on the south-facing slopes, and make jolly nice wine. So the presence of Roman Vinyards says very little about the average temperature.
It may tell us something about average summer rainfall, though, grapes being very susceptible to mildew.