Since the Soviets attack in June...the PCs will have to hold out a long time! And survive the Nuking of Anchorage (which I'm sure will be a huge part of this campaign) will be pretty key.
In looking at historical weather data of Kodiak Island (where I'm starting it), the average temp of June 1997 was 48.5 Fahrenheit.
There are huge gaps in the Arctic Campaign though, like from July-March '98, so I'm sure there'll be a place for Winterfest '97 in there somewhere.
I can't imagine anyone did much fighting though
. At least the Russians are used to it, and it won't be Eastern Front,1941-42.