We sailed the Island Princess northbound cruisetour starting September 4th, 2004 and had a great time. It was cool and sunny in every port (Ketchikan, Juneau, Skagway) until we got to cold Fairbanks on the land portion--about 18 degrees in the morning for the gold mine tour. Still, all we needed most of the time for comfort was a light windbreaker. Also, it snowed in Denali and at the Denali Princess Lodge. The lodge workers said it was the first snowfall of the season.
I have some photos if you would like to view them. There's a few shots of the Denali snow.
I would certainly go again in early September--great prices--no crowds.
Island Princess--Alaska Northbound Cruisetour 9/4/04
Disney Wonder--land/sea, 5/26/05
Coral Princess--Panama Canal, 10/5/05