Will this be enough insulation for my hands?

I'm off to Lapland in a week's time. I have pretty much all my kit but am unsure whether my hands will be sufficiently insulated. I have a pair of 'Extremities Sticky Thicky' gloves (a href="http://www.jackson-sports.com/Models.asp…" rel="nofollow"http://www.jackson-sports.com/Models.asp…/a as a base layer and a pair of Sealskinz Winter Mitts (a href="http://www.sealskinz.com/gloves/winter-m…" rel="nofollow"http://www.sealskinz.com/gloves/winter-m…/a to go over the top. Will this be sufficient for minus 25C, or should I get different mitts