Why are glass windows possible to be cracked in very cold region?

Thermal shock. If the exterior of the glass is cooled extensively, and the interior subject to much warmer temperatures (especially if it is abrupt, like a hot drink being spilled) the amount of stress built up between the thermal expansion of the inside and outside of the glass can cause it to shatter.

Thermopane Windows, which include two separate layers of glass, are not nearly as vulnerable to this as older single-panel Windows.