The season here runs from late April to the end of October, and the middle of it is not the best part of it.
June is warm without being heavy, the sea has come up to about 24 degrees, and the meltem has not settled into its August rhythm yet. Anchorages that will be full in six weeks are half empty. Late September is the same picture in reverse, with warmer water and cooler evenings.
August is busy and hot, and if that is when the school holidays fall then that is when you go. It is worth knowing what it means: the meltem fills in most afternoons on the Aegean side, the popular bays fill by four o'clock, and a good captain earns his keep by having you anchored before then.
Book June and September a year out. August, eighteen months.