Temperature crossed threshold

The Temperature crossed threshold trigger fires when a temperature reading crosses into a zone you define. A bedroom sensor crossing below 18°C on a cold night, a living room sensor climbing above 24°C in summer, a reading entering a target comfort range, or a reading escaping that range are all supported.

Use Temperature crossed threshold to automate heating or cooling when the temperature becomes uncomfortable, alert you when conditions in a room drift out of range, or coordinate devices that respond to specific temperature levels.

When you target more than one entity, the trigger’s Trigger when option controls when it fires.

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 crossed threshold 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 crossed threshold.
6. Under Threshold type, configure the zone the reading must enter for the trigger to fire:
   • Select Above or Below and enter a value to fire when the reading crosses that level.
   • Select In range and enter a lower and upper bound to fire when the reading enters the range from outside.
   • Select Outside range and enter a lower and upper bound to fire when the reading leaves the range (crosses past either bound).
   • For each option, you can enter a fixed temperature or 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. Under Trigger when (see Behavior), pick Each, First, or All to control how the trigger behaves when multiple entities are targeted.
9. Under For at least, set how long the reading must stay past the threshold before the trigger fires. Leave it at zero to fire immediately.
10. 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 crossed threshold is referred to as temperature.crossed_threshold. A basic example looks like this:

trigger: temperature.crossed_threshold
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"

This fires whenever the living room temperature sensor enters the comfort range (20 to 22°C).

To fire when the reading leaves a comfort range (escapes above 22°C or below 20°C):

trigger: temperature.crossed_threshold
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: between
  value_min:
    number: 18
    unit_of_measurement: °C
  value_max:
    entity: input_number.max_comfort_temperature

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.

Behavior with multiple targets

When you target more than one entity (or select an area, floor, or label that contains several), the Trigger when option controls how the trigger responds:

• Each (any in YAML, default): the trigger fires every time any one of the targeted entities transitions. For example, if you monitor three motion sensors in the living room and someone walks past sensor 1, the automation fires. When they walk past sensor 2 a moment later, it fires again. Every individual event counts.
• First (first in YAML): the trigger fires only on the first transition in the targeted group, then waits until all targeted entities have reset before it fires again. For example, if you monitor the same three motion sensors, the automation fires when the first one picks up movement (someone entered the room). The other two firing afterward are ignored, so you get one notification per “someone walked in” event instead of three.
• All (last in YAML): the trigger fires only after the last targeted entity in the group has fired, meaning all of them are now in the expected state. For example, if you monitor the lights in the living room, bedroom, and hallway, the automation fires only once all three have turned off. This is useful for scenarios like “start the robot vacuum only after every light on the floor is off,” so you know the room is truly empty.

Good to know

• Above and Below fire on the crossing moment only. Once the reading is above the threshold, the trigger does not fire again until the reading dips back below it and then crosses above again.
• In range (between) fires when the reading moves from outside the bounds into the bounds. Outside range (outside) fires when the reading moves from inside the bounds past either bound.
• A comfortable indoor temperature range is typically 20 to 22°C (68 to 72°F). Use Outside range with those bounds to fire the moment conditions drift out of that comfort zone.
• Pair this trigger with Temperature changed if you also want to react to smaller fluctuations between crossings.
• 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 off climate when temperature enters comfort range

This automation turns off the living room climate system the moment the temperature crosses into the comfort range (20 to 22°C), saving energy once comfortable conditions are achieved.

• Trigger: Temperature crossed threshold
• Target: Living room temperature sensor
• Threshold type: In range (20-22°C)
• Action: Set thermostat HVAC mode (state: off)

alias: "Turn off climate when living room is comfortable"
triggers:
  - trigger: temperature.crossed_threshold
    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"
actions:
  - action: climate.set_hvac_mode
    target:
      entity_id: climate.living_room
    data:
      hvac_mode: "off"

Automation: alert when bedroom temperature enters comfort range

After opening windows to cool down a stuffy bedroom, this automation alerts you the moment the temperature enters your preferred comfort range so you can close the windows.

• Trigger: Temperature crossed threshold
• Target: Bedroom temperature sensor
• Threshold type: In range (20-22°C)
• Action: Send a notification

alias: "Alert when bedroom temperature is comfortable"
triggers:
  - trigger: temperature.crossed_threshold
    target:
      entity_id: sensor.bedroom_temperature
    options:
      threshold:
        type: between
        value_min:
          number: 20
          unit_of_measurement: "°C"
        value_max:
          number: 22
          unit_of_measurement: "°C"
actions:
  - action: notify.mobile_app
    data:
      message: >-
        Bedroom temperature is now comfortable at
        {{ trigger.to_state.state }}°C

Automation: prevent false triggers with a delay

To avoid false triggers from brief temperature fluctuations when opening a door or window, add a For at least delay. This automation only fires after the temperature has been below 18°C for 5 minutes.

• Trigger: Temperature crossed threshold
• Target: Living room temperature sensor
• Threshold type: Below (18°C)
• For at least: 5 minutes
• Action: Set thermostat HVAC mode (state: heat)

alias: "Turn on heating when consistently cold"
triggers:
  - trigger: temperature.crossed_threshold
    target:
      entity_id: sensor.living_room_temperature
    options:
      threshold:
        type: below
        value:
          number: 18
          unit_of_measurement: "°C"
      for: "00:05:00"
actions:
  - action: climate.set_hvac_mode
    target:
      entity_id: climate.living_room
    data:
      hvac_mode: heat

Automation: trigger heating based on adjustable comfort temperature

Trigger the heating when temperature crosses below your personal comfort threshold. Use a number helper as the threshold so you can easily adjust it through the UI without editing the automation.

• Trigger: Temperature crossed threshold
• Target: Living room temperature sensor
• Threshold type: Below (entity: comfort temperature threshold)
• Action: Set thermostat HVAC mode (state: heat)

alias: "Turn on heating when crossing below comfort threshold"
triggers:
  - trigger: temperature.crossed_threshold
    target:
      entity_id: sensor.living_room_temperature
    options:
      threshold:
        type: below
        value:
          entity: input_number.comfort_temperature_threshold
actions:
  - action: climate.set_hvac_mode
    target:
      entity_id: climate.living_room
    data:
      hvac_mode: heat

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 changed: Triggers after one or more temperature readings change.