Hi,
I normally park my car in my garage, but am currently out of town for work, and am having to park outside, and it is about 5 degrees this week. Yesterday, for the first time ever, I noticed the paint along the passenger fender had not only cracked, but was coming off the car like pieces of a puzzle (Ie. large pieces). Having never been in this situation, I went to the local auto store, got some bondo, sanded the bare metal (which was all that was left, and bondo'd the area. I thought I had saved things. But tonight, I noticed a new area of cracks in the paint beginning to form.
My Question: What can I do to keep the paint from cracking in such cold weather conditions?
P.S. I have painted the car myself, using aerosol paint, but using correct methods. Have never had any problems over the past five years, of this hobby. Specifically, I used acrylic enamel aerosol paint.

Well, this kind of points out the difference between hobbyist and professional materials and methodology. When weather conditions, i.e. cold/hot/wet/dry are decent low solids materials like these canned coatings may look okay. When you start stressing them they fail because they just don't have the film build and elasticity of good pro coatings.
Just trying to stick fresh bondo back over the metal in these kind of temp.s is pointless. Don't know what to tell you....next paint work, go deeper into the hobby and get pro rattle cans made up by a auto paint jobber.....