While traveling in Greece, I discovered it can rain a fair amount in October. My dad and I drove around the mainland and visited several islands for a total of three weeks last year and experienced 4-5 days with showers. Although there were a couple of times I had to hide my sketchbook from the wet weather, It generally wasn’t a problem. The best part was the crystal clear views the rain provided, especially on Santorini were I could see for miles looking out over the Aegean from on top of the caldera.