Windshield developed a crack during a week with wild temperature swings. There was no incident leading up to the development of the crack that would have caused an initial chip or point of failure. The initial crack appeared during the day where the temperature went from the mid-60s to below freezing with precipitation in a matter of hours. Crack was not present in warm AM and appeared during cold PM. It grew (initial crack ended where the scotch tape is) during a day later that week with another wild temperature swings. Clearly a failure in the tempering process and insufficient QA for the component.