We are booked on Island Princess for May 28th. We are hoping to see wildlife and that the weather will be favorable. Our TA told us that the temperatures will be cool but not cold. Hope that is true. We are packing ponchos and umbrellas in hopes of NOT having to use them.
That is far and away the best advice you can give on weather in Alaska. I spent three consecutive seasons up there when I worked for Princess and there is nothing for sure. One week you are walking around in shorts and T's and the next in sweaters and raincoats.
I have cruised from Seattle on 6-4 and from Vancouver on 8-28. Both times were great. I have flown up to Alaska the end of May as my cousin lives there and it was still great.
If you click on this link, http://joslin-family-photos.smugmug....6364#138094934 you will see the weather in Alaska on the Inside Passage, Note there are some swimming and some in jackets. The rest of my cruise photos are in the link below.
We went to Alaska last Sept with Princess 12 day heart of Alaska tour. We did the land part first and sailed 7 days from Whittier to Vancouver. We had great weather, one day of rain while on the ship at sea. We know this was a very lucky trip weather wise, even the natives couldn't believe it. Its truly a crapshoot with the weather in Alaska. We happened to luck out. In the mornings it was 25 to 35 degrees F. by afternoons I was wearing shorts and tee shirts. As for best time to go, I was told by the natives from mid June to mid August. In May they said the bugs were bad and Sept its usually colder, but the price is cheaper. As for the smooth sailing, there is one day you are at sea outside the passage, thats the day we had the rough seas, they don't bother us but it did some people. All in all we had a great trip and are looking forward to going back again someday. JC