Spring (April – June) and Autumn (September – October) are the best months to visit Greece for a peaceful holiday after the rush of summer. The days are long, and the weather is mild. If you're looking to enjoy yourself at the beaches, the water is warm and inviting in Autumn.
Is everything open in Santorini in October?
Many flights, as well as quite a few restaurants and hotels, close up for the season during October, so you may find most things still open and a fair few people around at the start of the month and more things closed and fewer fellow visitors as October draws to a close.