We're doing SB on Diamond. I'm wondering how cold it will be on deck and/or our balcony for glacier viewing days and afternoons, as well as in ports (Skagway, Juneau, Ketchikan).
Thank you in advance.
Most of southern Alaska has a very mild climate, with daytime temperatures in the 60's to 70's, and sometimes into the 80's, and nighttime temperatures in the 50's to 60's.
That said, the calving action of the glaciers provides a steady supply of ice into the bays that have them, and ice water invariably has a temperature of 32 degrees. The air above those bays is not much warmer, either -- upper 30's is typical. Thus, when viewing glaciers, you probably will appreciate a winter jacket, hat, and gloves. The same is true of shore excursions that land on glaciers, for which you also will want snow boots.
I should also mention that the southern part of the inside passage is a temperate rain forest. Ketchikan is the wettest city in North America, with over 250 days of rainfall per year, and rain is also about a 50/50 possibility in Juneau. On rainy days, temperatures in these ports tend to be in the lower 60's. You'll definitely want a waterproof light jacket and hat in these ports.