They are coming from Idaho, they should be able to handle our winters. Boise actually gets less sun in the winter than Boston does, for instance 105 hours of sunlight in Boise in December versus 142 hours in Boston (it actually gets a smaller percent of its possible sunlight in the winter than Boston, only around 30-40% sunlight in winter in Boise versus 50-60% in Boston). That said, Boise is sunnier in the summer than Boston, and also much hotter and dryer in the summer.

Average winter temperatures are almost the same between Boise and here, it's a difference of only a couple degrees.