Oscillators of all kinds are temperature dependent.

That's why the most stable ones are insulated and ovenized[1].

So an AC failure which would lead to higher room temperatures would lead to stronger or more frequent correction by the NTP client, as the local oscillator would drift more.

Not sure about the fire case though. I mean the same applies there but I'm not imaginative enough to think of a realistic scenario where NTP would be useful for averting a fire.

[1]: https://blog.bliley.com/anatomy-of-an-ocxo-oven-controlled-c...