The temperatures at which a US built Smartpack can be safely stored (not operated) are dictated by the LCD:
Storage Temperatures are: -20 ºC to 60 ºC, this is -4 ºF to 140 ºF. It is not save for the pack to stay at -20 ºC for more than 48 hours. Safe permanent storage tempuratures should be limited to -10 ºC to 50 ºC, which is 14 ºF to 122 ºF
Operating Temperatures are : 0 ºC to 50 ºC, which is 32 ºF to 122 ºF
As with any LCD response will slow in cold temperatures, and you should allow the unit to warm up to the minimum operating temperature before operation.