The climatic conditions on the volcanoes are extreme as well.
To realise how particular it is, just think about a spot in the middle of Mediterranean sea, not far from the northern African coasts, where in a small range you can find different environmental conditions and flora in common with places like Nordics and Africa at the same time.
Volcanoes creates micro-climate within a single region.
In summer, even though temperatures can arrive to 40°, it’s easy to experience a gap of temperature of 20° in a range of 5 miles and 20 minutes driving, just moving in altitude.
In the winter, temperatures go easily below the 0° and vines disappear under a meter of snow.
Wind flows from everywhere.
Cold air coming from the top of the volcano and temperated-salty air coming from the oceans surrounding them.
On volcanoes vineyards and vines are stressed and pushed to adapt their metabolism to this sudden changes of temperature.