Squirrels live in winter burrows during the winter months, which can be found underground or in hollowed out trees. Unlike many rodents, squirrels do not hibernate during the winter but they keep their activity to a minimum while living off fat reserves.
Squirrels can generally be seen out foraging for food during the winter as long as the temperatures are not below 30 degrees Fahrenheit and it's not snowing or raining. Squirrels also rely on cached stores of food during the winter. If enough food has not been stored for the winter and the squirrel loses its vital fat insulation layer, it generally will be unable to survive the winter.