If the system wasn't set then it can only be the 24hr monitored side of the system as it came up ZONE 7 , there should have also been a tamper light lit if the panel/keypad is led display if its led crystal display it would day tamper ZONE 7, if the system is two wire with resistors fitted at the detector temp can effect them ,either way a site visit would be required to check.for corrosion etc depending on what and where it is covering ie external door(contact) garage area ( pir/DT)

It is most likely that the cold weather caused a fault with either the detector on zone 7 or the cabling to that detector

The could can cause issues on intruder alarm but not directly on devices because almost devices operate on temperatures -20 to +50 degrees.
In this case i will check the cable quality if we are talking about the cold temperatures.

It is very difficult to say either way without knowing what typ of system yu have. If you have a wired alarm system and it was not set then it is likley to be a tamper fault that has caused the issue. This could be anything from a fautly tamper switch to a damaged cable (Usually rodents in lofts!).

If your system is wireless, then cold weather could have been the cause. When lithium batteries get cold they can stop producing the voltage required to keep sensors running and transmitting to the control panel. Depending on the panel type you have, this will usually bring up an audible warning and zone fault.
It would be best to have a professional come and take a look and service your system to ensure it is working correctly and does not disturb you in the middle of the night again! I hope this helps :-)