Have a scarf, a pair of gloves, a light jacket with a hood to protect against the rain, a wool sweater and some sweatshirts (not sure what these are called in that truly wonderful place called Australia - been there and have read "in a sunburned country"). A sweatshirt with a hood could replace the jacket if necessary.
Recommend renting a car in Juneau and Skagway. Alos hike the East Loop trail when you visit the Mendenhall Glacier outside of Juneau. Take the spectacular highway outside of Skagway up into the Canadian Yukon. The train does essentially the same trip but it is much more expensive.
Hope that this helps.