Lightweight clothing, long cotton dresses, short tops, t-shirts, sleeve-less shirts, skirts and (high-waisted) shorts as well as swimsuits (the water is usually warm enough to swim in late spring and fall as well) are a very appropriate choice in summer.
It’s recommended to wear flat shoes for the evening, hiking sandals for the day and flip flops for the beach.
It’s good to take a light jacket for the evenings (especially from September on when days can be very hot but mornings and evenings chilly and windy).
The general mildness of the weather of the island all the year round is because of its southern location in the Mediterranean Sea as well as because of its formation around the volcano.
Summer starts in May and ends in October on the island. This period is known as the “dry season” and is characterized by a continuous bright sunshine that normally lasts for 12 hours.
The winter months in Santorini are from November to April when the island gets more rainfall that any other time of the year and that’s why this period of time is known as the “wet season”.