A325 Low Temperature Service / A320

[commocheck]

I realize A325 hardware is not considered appropriate for low temperatures, however I was curious if anyone could point out the lowest service temperature for A325 bolts. I have not been able to locate the acceptable temperature range for A325, just that they should not be used in low temperatures. Low temperatures is kind of a relative descripion. What point should I switch to A320 hardware.

Thanks in advance.