Smoke Detector False Alarm - Heat Related?

So I'm on a 2 week vacation, 2000 miles from home, and lying in a hammock looking at the stars at 11:30pm and my phone rings - Ring Security was calling to let me know my 2nd floor smoke detector was going off. It's one of the First Alert CO2 / Smoke detectors (I think they've now been discontinued?) - Not being anywhere close to home and naturally being worried about my house burning down, I called my local police department (I live in a small town where the station is a few blocks away and the police officers are also the firemen). Within minutes an officer went right over, called me on his personal mobile, I unlocked the door remotely, and he verified it was a false alarm - but that it was very hot upstairs. Because my AC was set to vacation mode it was around 80 degrees near that alarm - does heat / humidity set these things off? I've had them installed for over a year with no issues. Any thoughts as to what causes false alarms if no cooking, legitimate CO2 / fires, etc?