Thermals
Monitor your device's thermal state and heat-related constraints.
Overview
The Thermals tool helps you understand when your device is getting hot and whether iOS is applying thermal limits that can reduce performance.
Table of Contents
Main Sections
Thermals is a single scrolling screen with:
- A hero gauge that visualizes the current thermal state and a percentage-style level.
- A thermal stack that highlights the current state across Nominal, Fair, Serious, and Critical.
- A Current State card.
- A Recommendation card with guidance based on the current thermal state.
Thermal States
Lirum uses iOS thermal states, each with a color and icon:
| State | Color | Icon | Gauge Level |
|---|---|---|---|
| Nominal | Green | Checkmark | 0% |
| Fair | Yellow | Warning triangle | 33% |
| Serious | Orange | Flame | 67% |
| Critical | Red | Stop sign | 100% |
The animated background gradient shifts to match the current state color.
The thermal stack shows all four states and uses a cascade effect -- all states up to and including the current level are lit. For example, if the state is Serious, then Nominal, Fair, and Serious segments are all filled.
Lirum records a state history of thermal state transitions with timestamps (up to 100 entries), letting you track how the thermal state has changed over time.
What You Can See
- Thermal state (for example: nominal, fair, serious, critical)
- Indicators that performance may be reduced due to heat (device/OS dependent)
- Related context from other tools (CPU usage, charging, background activity)
Notes
- Available thermal details vary by device model and iOS version.
- Sustained high CPU/GPU load, charging, direct sunlight, and poor ventilation can trigger thermal limits.
Notes And Limitations
- Thermals reports the system thermal state, not a physical temperature sensor reading.