Since 1994 I have been visiting the Greek islands at least once a year
In these 20 + years I have experienced all the seasons, and have taken tour groups on different dates between May-September
In my opinion the mid-end of June has been the most rewarding. Why?
Tourism industry workers are fresh and excited. The taverns you visit are a little more hospitable, waiters seem to have more time to help you and tables are still available at popular eateries
Ferry transportation is less crowded and you are able to get a seat, even to the popular islands
Taxis are obtainable, and other forms of public transport are not as crowded, (during August you will have to wait in a large line)
You are avoiding the school holiday period. Once school and university is out, there are hoards of families and children cramming for a spot on all the best beaches
Accommodation is affordable and available, unlike peak periods that need to be booked well in advance, and usually have a no cancellation and pay on booking policy
The weather! No more long hot days and even longer sleepless nights. June provides a enough sunshine to play during the daytime and a cool breeze to rest and unwind when the sun sets
September is also a great time to consider, being end of the season and school is back in session. It is still a great temperature to enjoy outdoor activities, and you can obtain accommodation. Do be mindful however that the summer “buzz” is slightly lacking, and the service industry workers may not be as accommodating as in June.
Well, to be fair it was definitely a long, hot, busy summer!!