Check out
http://www.wunderground.com and pull up the weather data for any of those cities you mentioned and you'll see all kinds of graphs and charts that will show you the differences.
Everyday I look at Anchroage (99501), Barrow (99723), Bethel (99559), Fairbanks (99701), Homer (99603), Juneau (99801), Ketchikan (99901), Kodiak (99615), Nome (99762), Seward (99664) & Sitka (99835).
Also check out the Wunder Photos section they have on the website, do a search for Alaska and Alaskan or any of the cities in Alaska and see some fantastic pictures of some awesome scenery.