Large temperature differences between the inside and the outside of the windshield do put stresses on the glass and can cause it to crack (or a crack to develop or extend from a chip or other flaw). Living in an area with cold winters, I can say it also tends to work the other way, when you have subzero temperatures outside and the heater/defroster valiantly trying to keep the vehicle interior somewhat civilized.
If the crack goes to the edge of the window, under the gasket/seal, it's possible that there was a chip in the glass there and that's what started the crack.