Weather in May is wet! and cool - bring rain clothes and layers. If you don't have a polar fleece - invest in one - you will be happy you did - especially if you are going on any excursions - you can purchase them from Lands End, Cabellos, Eddie Bauer.. Also bring "mosquito dope.." also known as OFF -Skintastic, Cutters Advanced or Avon's Skin so Soft -when it's wet - there CAN BE mosquitos - but you will still have a great cruise -Enjoy our state ! Happy cruising..