As the myrmecologist James Trager once said, if I'm recalling correctly, pretty much all Camponotus this far north can survive sub 32F temperatures. His garage will never get below freezing. They'll be fine. You must understand that Camponotus pennsylvanicus stay in the wood year round. That doesn't offer them any protection from extreme cold. When we hit -60F up here last winter, the Camponotus were at the same temperature. They will be fine.
Currently Keeping:
Trachymyrmex septentrionalis
Pheidole pilifera
Forelius sp. (Monogynous, bicolored) "Midwestern Forelius"
Crematogaster cerasi
Pheidole bicarinata
Aphaenogaster rudis
Camponotus chromaiodes
Formica sp. (microgena species)
Nylanderia cf. arenivega