The horses spent most of their time in the heated barn, only venturing outside for a few hours daily. The Zoo got 100 bales of hay for the winter, so the horses ate fine.
Also, don’t mindlessly follow Google directions. Google had people diverting from I-95 through the twisty, winding, hilly roads around the Zoo even though these roads are not plowed, resulting in multiple abandoned out-of-state vehicles, 18-wheelers, and even busses blocking roads preventing the power company from repairing downed power lines.