Not so much the cold but the condensation caused by cold. Diurnal (day/night) heating and cooling, can cause water vapor in the air to condense on surfaces and contaminate oils. This is more of a concern with partial containers, naturally.
Gelation in oils is both time and temperature dependent. The newer oils "age" more slowly but the effect is still there. I always advocate changing oils every spring (at least). This is even if the car was minimally driven over the past year.
Gelation is generally less of a problem with synthetic oils. This is another advantage (of a few) over plain mineral based oils.