Expect cold if you go up the White Pass and on or by by the glaciers, expect wet everywhere and when it isn't raining or drizzling it could be soon and expect some warm even hottish sunshine, oh yes and some wind because that is their weather throughout the summer. It is beautiful and worth going to but as it says, be prepared for anything.... Neil.
If you are going to Alaska in the Northern Summer (which is the only cruising period)the weather in the Southern parts will be very similar to that of the UK. It can be changeable and it can be wet but equally can be pleasantly warm. In the Winter it can be a little different!!
Take a warm jacket etc as you will be amongst the glaciers and snow, the weather can be biting cold or similar to when the sun shines on a sking holiday.