Temperature changed

The Temperature changed trigger fires after a temperature reading changes. Temperature shifts gradually as heating or cooling systems cycle, rises when the sun heats a room in the afternoon, or drops overnight. Use the threshold type to filter which changes matter to your automation.

Use Temperature changed to log temperature trends, trigger heating or cooling when the temperature in a room changes noticeably, or alert you when a sensor reading shifts in a way that might signal a problem.

Using this trigger from the user interface

If you prefer building automations visually, Home Assistant walks you through this trigger step by step. You pick what to watch, tweak a few options, and save. No YAML knowledge required.

To use Temperature changed in an automation:

1. Go to Settings > Automations & scenes.
2. Open an existing automation, or select Create automation > Create new automation.
3. In the When section, select Add trigger.
4. Select what you want to monitor. Under By target (see Targets), pick the area your temperature sensor is in (like your bedroom or living room). You can also select a device, a specific entity, or a label.
5. From the triggers shown for that target, select Temperature changed.
6. Under Threshold type, configure what kind of change fires the trigger:
   • Select Any change to fire on any change, regardless of direction or new value.
   • Select Above or Below and enter a value to fire only when the new reading is above or below that value.
   • Select In range and enter a lower and upper bound to fire only when the new reading falls inside the range.
   • Select Outside range and enter a lower and upper bound to fire only when the new reading is outside the range.
   • For each option, you can enter a fixed temperature, pick a sensor entity or a number helper entity as the threshold.
     • If you don’t have a number helper, you can create one by selecting Create a new number helper.
7. Under Unit, select the temperature unit (°C or °F) to use for the threshold comparison.
8. Select Save.

Options in the UI

Using this trigger in YAML

If you work directly in YAML, or you want to know exactly what Home Assistant does under the hood, this section has the technical reference. It lists the field names you use in YAML, their types, and which ones are required.

In YAML, Temperature changed is referred to as temperature.changed. A basic example looks like this:

trigger: temperature.changed
target:
  entity_id: sensor.living_room_temperature
options:
  threshold:
    type: above
    value:
      number: 20
      unit_of_measurement: "°C"

This fires whenever the living room temperature sensor reading moves to a value above 20°C. To fire on any change regardless of direction or value, use type: any and omit value.

To fire only when the new reading is within a comfort range:

trigger: temperature.changed
target:
  entity_id: sensor.living_room_temperature
options:
  threshold:
    type: between
    value_min:
      number: 20
      unit_of_measurement: "°C"
    value_max:
      number: 22
      unit_of_measurement: "°C"

To fire only when the new reading is outside a comfort range:

trigger: temperature.changed
target:
  entity_id: sensor.living_room_temperature
options:
  threshold:
    type: outside
    value_min:
      number: 20
      unit_of_measurement: "°C"
    value_max:
      number: 22
      unit_of_measurement: "°C"

Options in YAML

YAML sometimes provides additional options for more complex use cases that are not available through the UI.

threshold:
  type: outside
  value_min:
    entity: input_number.comfort_temperature_min
  value_max:
    number: 24
    unit_of_measurement: °C

Targets of the trigger

This trigger requires a target. The target is the object that Home Assistant will watch. You can select a single entityAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more], a device, an area, a floor, or a label as a target, and Home Assistant will watch every matching temperature entity behind that target.

• Entity: one specific temperature entity, such as temperature.living_room.
• Device: every temperature entity that belongs to a device.
• Area: every temperature entity in a room or area.
• Floor: every temperature entity on a floor.
• Label: every temperature entity that shares a label.

You can also select different target types in one trigger. For example, you can add a specific entity and an area as targets in the same trigger to monitor both of them at once.

Good to know

• The threshold type controls both the direction and the landing zone of the change. Use Above or Below to filter by direction, In range to fire only when the new value is inside a range, and Outside range to fire only when it escapes a range.
• Use Any change to fire on every change regardless of direction or where the new value lands.
• To react only when temperature first crosses a specific level, use Temperature crossed threshold instead.
• The trigger works with climate entities, water heater entities, weather entities, and sensors with the temperature device class.
• Climate, water heater, and weather entities that don’t report a current temperature attribute are automatically excluded from the trigger. Only entities with a valid temperature value can fire the trigger.
• All temperature values are automatically converted to the unit you specify. For example, if your sensor reports in Fahrenheit but you configure the trigger in Celsius, the conversion happens automatically.

Try it yourself

Ready to test this? Go to Settings > Automations & scenes, create a new automation, and add this trigger. Save the automation, then change the state of the targeted entity to watch the trigger fire on your actual entitiesAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more].

More examples

Real scenarios where this trigger fires in automations and scripts. Copy any example and adapt it to your setup.

Automation: turn on heating or cooling when temperature leaves comfort range

When the living room temperature changes to a value outside the comfort range (20 to 22°C), this automation turns on heating or cooling to restore comfortable conditions.

• Trigger: Temperature changed
• Target: Living room temperature sensor
• Threshold type: Outside range (20-22°C)
• Action: Set thermostat HVAC mode (state: cool)

alias: "Adjust climate when living room is uncomfortable"
triggers:
  - trigger: temperature.changed
    target:
      entity_id: sensor.living_room_temperature
    options:
      threshold:
        type: outside
        value_min:
          number: 20
          unit_of_measurement: "°C"
        value_max:
          number: 22
          unit_of_measurement: "°C"
actions:
  - if:
      - condition: template
        value_template: "{{ trigger.to_state.state | float < 20 }}"
    then:
      - action: climate.set_hvac_mode
        target:
          entity_id: climate.living_room
        data:
          hvac_mode: heat
    else:
      - action: climate.set_hvac_mode
        target:
          entity_id: climate.living_room
        data:
          hvac_mode: cool

Automation: alert when temperature leaves comfort range

This automation sends a notification when any room temperature drifts outside the comfort range of 20 to 22°C, helping you maintain consistent conditions throughout your home.

• Trigger: Temperature changed
• Target: All temperature sensors (label)
• Threshold type: Outside range (20-22°C)
• Action: Send a notification

alias: "Alert when temperature leaves comfort range"
triggers:
  - trigger: temperature.changed
    target:
      label_id: temperature_sensors
    options:
      threshold:
        type: outside
        value_min:
          number: 20
          unit_of_measurement: "°C"
        value_max:
          number: 22
          unit_of_measurement: "°C"
actions:
  - action: notify.mobile_app
    data:
      message: >
        Temperature in {{ trigger.to_state.name }} is {{
        trigger.to_state.state }}°C

Automation: alert when temperature enters comfort range

Send a notification whenever the bedroom temperature changes to a level within your personal comfort range. Use number helpers for the range bounds so you can easily adjust your preferred temperatures through the UI.

• Trigger: Temperature changed
• Target: Bedroom temperature sensor
• Threshold type: In range (entity: comfort temperature min and max)
• Action: Send a notification

alias: "Alert when temperature enters comfort range"
triggers:
  - trigger: temperature.changed
    target:
      entity_id: sensor.bedroom_temperature
    options:
      threshold:
        type: between
        value_min:
          entity: input_number.comfort_temperature_min
        value_max:
          entity: input_number.comfort_temperature_max
actions:
  - action: notify.mobile_app
    data:
      message: "Bedroom temperature is now {{ trigger.to_state.state }}°C, within your comfort range."

Still stuck?

The Home Assistant community is quick to help: join Discord for real-time chat, post on the community forum with the trigger you’re using and what you expected to happen, or share on our subreddit /r/homeassistant.

Related triggers

These triggers work well alongside this one:

• Temperature crossed threshold: Triggers after one or more temperature readings cross a threshold.