The novel clearly takes place in winter in Moscow, and the novel's chock full of cold, wintry imagery. Here are just a few frosty gems:
In these examples, cold is associated with: isolation ("Red Square is deserted"); darkness ("thick black ice"); obscured vision ("icicles hanging over the frozen windows"); and imprisonment ("an ice cave...a peephole in a prison cell's door").
So, what might all of these things have in common? Well, they all seem to relate in some way to the effects of the political system in power in the 1950s USSR. People are isolated from each other because they're afraid. It's a dark time in which people can't get a good handle on what's going on. And lots of people are being locked up in prisons (some in the literally freezing wasteland of Siberia and the system of gulag prisons for which the Soviet Union was notorious).