Before everyone decides to flame this post, he is actually correct. Lots of research shows that cold temps increase metabolism, mainly through induction of thyroid hormone receptor alterations, 5-deiodinase activity, and uncoupling proteins.
Chronic exposure will, unfortunately, increase the deposition of subcutaneous bodyfat to increase insulation.
Zaninovich AA, Rebagliati I, Raices M, Ricci C, Hagmuller K.
"Effects of thyroxine on rat brown fat and muscle thermogenesis in the cold."
Endocr Res. 2000 May;26(2):231-45.
Larkin S, Mull E, Miao W, Pittner R, Albrandt K, Moore C, Young A, Denaro M, Beaumont K.
"Regulation of the third member of the uncoupling protein family, UCP3, by cold and thyroid hormone."
Biochem Biophys Res Commun. 1997 Nov 7;240(1):222-7.