-— During the coldest part of winter my wife will often just shelve refrigerated items in the garage to keep them cold -—
You can also put an old refrigerator out there. It won’t have to work very hard, but it will keep a more stable temp.
My understanding is that cold temps can make the inside temp of a refrigerator inconsistent, that the thermostat can be confused enough to not maintain as tight of a set temperature, and that the freezer may be affected in a more dramatic way, depending on the model.
Also, in deep cold, things may freeze that shouldn’t be freezing, since the refrigerator will simply shut off at around 36 degrees and be nothing but a cabinet.
In very cold winters an ice chest is still used for beer, but it is used with a hot water bottle inside of it, instead of ice.