We're cruising to Alaska May 2, leaving from Vancouver, Canada and returning to Seattle May 9 on NCL. I assume the weather will still be a bit brisk, so should I even bother to bring capris or just jeans? We also decided to forego formal night to make the packing lighter.
Layers! Including light weight rain gear. I like disposable ponchos because they take up minimal room and weight. It can be cool and rainy or sunny and quite warm. I would not bother with shorts or capris myself, but I would find some not true formal, but dressy clothes. A pair of nice black slacks with a dressy top can do the trick. Depends a lot on which cruise line you are going on.
You may be surprised by how much warmer it is. Sitka never goes below freezing, even in winter. Much of the Alaskan coastline is a temperate rain forest. The ocean currents make a huge difference, so be prepared for warmer, not colder. That's why I suggest layers...you can always shed a layer or two. I've done Alaska in May and Sept, and both times had days when a t-shirt was adequate. You just can't count on that.
NCL no longer has true formal nights, it is optional. A lot of people do dress up, but at least you will still be able to eat anywhere you choose without worrying about the dress code.
two years ago we cruised Alaska in early May and ended up with wonderfully sunny days and while we were docked in Juneau they even opened the sliding panels to the indoor pool and people were laying around the pool in swimsuits and shorts. So you never can tell. It is cool on deck especially going through the glaciers so like people have said before me, bring short sleeve, long sleeves, warm pants, slightly cooler pants, and jackets that you can layer easily.