How can thermal stresses lead to weathering?
Extreme thermal stress, such as the one affecting rocks exposed to an alternate hot-cold climate, may cause fractures in the material allowing for faster mechanical deterioration. The fractures also facilitate the circulation of water within the rock with further weathering.
An example of such effect happens in areas where very cold seasons alternate with warmer ones and it is called "cryoclastism". Typically rocks on mountains are exposed to such type of weathering. The water penetrates into the rocks through small crevices, pores and fractures, it then freezes and breaks the rock with its expanding pressure.
In the desert very hot days followed by chilly nights can also cause a form of thermo-clastism generating tensions within the rocks able to break them.