Winter squeak/creak?

He is asking about a winter squeak he is hearing. He says it's definitely not a "rattle" like something is loose, but more of a squeak or creak noise. He says it only happens when the car hits bumps or goes up a driveway, etc... He also said that in the warm weather, he doesn't hear it, only when it's cold. We're in PA, so it's pretty cold right now. He mentioned it last winter too. I haven't heard it myself, so I can only go on his description. He has been quite meticulous about upkeep on the car, as was I, so it's a well kept car.
I've read about sway bar bushings making noise, but I would think if it was the bushings, it would do it year round? Could it be something in the body? I know a squeak/creak can be a bear to trace down, but wondering if anyone knows of a common source for cold weather noises in the C5?










