A room at 88°F and steady is a different situation from a room at 88°F that was 78°F fifteen minutes ago. The second one is going somewhere.
So units watch the rate of change as well as the value. A sustained rise of about a quarter of a degree per minute, held over at least five minutes within a twenty-minute window, counts as a spike.
- Wi-Fi units accelerate to their fastest safe reporting rate.
- Cellular units shorten their sync interval and push immediately on the transition, rather than waiting for the next scheduled check-in.
Elevated reporting ends when the situation does — the level returns to Safe or the rapid rise stops. There is also a hard six-hour ceiling, so a stuck sensor can't keep a cellular unit transmitting indefinitely.
Reporting faster during a real heat event costs a trivial amount of cellular data — a few thousandths of a dollar for a full shift. Data cost is never a reason to report less during an actual emergency.