Quoting from Vartech Systems, a supplier of rugged displays:
LC displays (LCD) have a well-defined isotropic or operating temperature limit, above which the actual liquid crystal molecules will lose their orientation and will assume a random orientation instead of ‘twisting’ through the light valve.
Basically, the crystal orientation in the liquid crystal gets randomized, and the effect is that light can't pass through, so the image is darkened. I suspect that as the temperature straddles that operating temperature limit you may get a dim image where some crystals are still more or less in alignment while others are randomized.
Reading a bit further on,
Isotropic conditions will cause positive image displays to
become dark (see image below), while negative image LCD's become
transparent. This is the Nematic-to-Isotropic Transition Temperature
or NI Transition.
Most computer LCDs are positive image displays, and thus you wind up with your dark display.
The site goes on to note that temperatures above 100°C (212°F) can permanently damage the coating on LCD displays, though Samsung claims that storing your display at temperatures above 45°C (113°F) can damage it, so it's possible that Vartech's 100°C threshold is specifically a property of their ruggedized displays.
Vartech also mentions that as temperatures drop the viscosity of the LC increases, resulting in slower response times (which will first manifest as "ghosting", and further as very slow image updates/transitions, like a bad PowerPoint slideshow in slow-mo). The site doesn't make mention of whether excessively low temperatures can permanently damage a display, but the line
Low temp effects are usually reversible
suggests that it is at least theoretically possible for extremely low temperatures to cause irreversible damage.