I have also wondered about that and you made me get off my duff and do some googling:})
Here is a table that I lifted from http://americas.kyocera.com/kicc/lcd...pconsider.html and seems to be pretty representative of several sites I visited.
Typical Temperature Specs
LCD Family Item Celsius Fahrenheit
Standard STN Operating Range 0 to 50/60 32 to 122/140
Standard STN Storage Range -20 to 60 -4 to 140
Standard TFT Operating Range -10 to 70 14 to 158
Standard TFT Storage Range -20/-30 to 80 -4/-22 to 140
Wide Temp STN Operating Range -20 to 70 -4 to 158
Wide Temp STN Storage Range -25 to 75 -13 to 167
There are additional effects listed due to temperature, but I think you get the idea.