Douglas Harper's Etymology Dictionary
Usage examples of "sub-arctic".
At the present day, the sub-arctic and northern temperate productions of the Old and New Worlds are separated from each other by the Atlantic Ocean and by the extreme northern part of the Pacific.
And to this continuity of the circumpolar land, and to the consequent freedom for intermigration under a more favourable climate, I attribute the necessary amount of uniformity in the sub-arctic and northern temperate productions of the Old and New Worlds, at a period anterior to the Glacial epoch.
He hadn't thought about it before because no one took a jacket to the dance, and during intermissions when people went on deck they could stand a few minutes of sub-Arctic air.