It depends where you go. The more northern islands are going to be less sunny by end of Sept. Thassos and the Ionian islands can be quite rainy and some resorts will be closing down so menus will be limited.

Rhodes, Kos or Crete would probably be your best bet as they are further south and are big islands so should still be open.

You will probably find if you book the last week of Sept that your return flight comes out empty to pick the last of the holiday makers up on some of the smaller island (this happened to my friend in Santorini).

Crete should still be open until mid Oct. Not sure if anyone else can give any different advice on other islands?

I always go to Rhodes in October and for the past 8 years have had lovely weather. However with the way our weather has been this year I'm keeping my fingers crossed that the trend will continue!

We have had quite a few holidays in various parts of Greece in late September/early October - latest returning home mid October. The weather has mostly been good enough for the beach, cooling of at night. We've had the odd half day of rain, often just a brief thunderstorm that has cleared in a couple of hours. Late September is a good time to visit and not too crowded.

I've been to Rhodes in October( coming home the last week of the season) and we had gorgeous weather. So September will be lovely

We often go to Symi in September/ October and the weather is very good. We needed the air c.o.n. in the first week of October last year and were still sitting out in the evenings.

Symi is certainly a good choice for late weather but not too good for sand. We have been to Crete, Rhodes, Kos and Samos in October and they all fit the bill but the tavernas do start to close after mid month

We have been to Zante, and Corfu in september and the weather was good most of the time with an odd day of heavy showers, but still very warm.