I know this cruise is past, but our experience was from mid-May, Venice to Athens, including Kusadasi, Turkey. The beaches were too cold to swim, it was only warm enough to go to the pool on board one day. We took a lot of layers and wore most of them every day. We usually travel with water-proof jackets that fold into a pouch. We combined those with light sweaters and t-shirts. We would start off the day in all 3 layers and shed as the day warmed up, putting them back on for evening. It was warmer in Athens, got up to near 100 the day we hiked to the Acropolis, but Venice was cold and rainy. You never know what you will find, so be prepared for everything.