Depends on many factors, but cold is not going to be the primary issue.
The problem you are going to run into is condensation at low temperatures, that moisture will pose a greater threat than cold will.
Can you elaborate a bit more on the question here? That would help get some more solid answers.
Is this hypothetical limits? Is your PC next to a window in winter? Storage unit? etc.
Assuming weather dosent get in (ie rain) I wouldnt be worried about that.
Back in college my desk was right next to a window, weather in Santa Cruz was very cold and humid all winter, my monitors got rained on more than once by a surprise downpour.