As a Seahawk fan that regularly bet against my own team in the NFL pick'ems contest, I'll tell you why the Seahawks might actually have an edge against the Vikings:
They ALREADY beat the Vikings (by a large margin) in cold weather this year. This will be a repeat performance, only they will have less injured players to deal with. And from the looks of it, the Vikings will have more.
Lynch just got done healing up as well as Kam Chancellor, and Wilson didn't even play in most of the second half of the Cards game so he could stay safe and healthy. Several other Seahawk players are healing up as well. Note that they had a lot more injured players their first time playing the Vikings this year, and the weather was almost just as cold.
Which is not to say the Seahawks beating the Vikings is a sure thing. Only it's more likely they'll win than they'll lose. And besides that, if you want to look at recent performances- The seahawks just got done slaughtering the Cards (the CARDS, possibly the best team in the NFC) and the Vikings barely beat Green Bay, which has been mediocre as of late.
Again, teams fluctuate game to game and for that very reason anything could happen. I still think the Hawks have the odds in their favor.