Layers, mix and match what you have. lightweight lined jacket, knit hat and gloves, rain gear. 2 pair of walking shoes. The ship laundry is a zoo near the end of the cruise, you are better off, maybe considering doing laundry on day 3 or 4. Then send out end of your week.
I always do my laundry off ship in Skagway. Located at State and Second, fast drying propane dryers, I can be done usually about 1 1/4 hours. The ship dryers take that time alone. The time allows some shopping down the block if of interest. The SMART bus drops off 1 block away.
Yes pack a pair or 2 of shorts, they take up little room, but don't forget at least 1 sweatshirt/sweater etc.