T.A.N, this just isn't true about the weather in my own humble experience. Yes it can be unsettled but having holidayed in various parts of Greece and on her islands, nearly every year in October for the last 15 years, including the last week of the month, I have only seen 1 day of rain. I have experienced the odd shower or two in the evenings but nothing more. I'm not saying it doesn't rain or get a little chilly but overall the weather in Greece is no more unpredictable during those months than Spain, Turkey, Italy etc and even Tunisia. The weather cannot be *guaranteed* anywhere
I have had far more bad weather in May than September and October.