Thermostat is on

The Thermostat is on condition passes when a thermostat 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] is currently on (in any active mode such as heating, cooling, or fan only). Use it to gate an automation so it only runs when a specific thermostat (or every targeted thermostat) is already active.

When you target more than one thermostat, the condition’s behavior option controls how the check combines results. You can require any targeted thermostat to be on, or demand that all of them are.

Using this condition from the user interface

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

To use this condition in an automation:

1. Go to Settings > Automations & scenes.
2. Open an existing automation, or select Create automation > Create new automation.
3. In the And if section, select Add condition.
4. From the search box, search for and select Thermostat is on.
5. Under Targets, select the thermostat entity, an area, a floor, or a label.
6. Under Condition passes if, pick Any or All to control how the check behaves when multiple thermostats are targeted.
7. Select Save.

Options in the UI

Using this condition 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, refer to this condition as climate.is_on. A basic example looks like this:

condition: climate.is_on
target:
  entity_id: climate.living_room

This passes when the living room thermostat is currently on in any active mode.

Options in YAML

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

Targets of the condition

This condition requires a target. The target is the object that Home Assistant will check. You can point the condition at 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, and Home Assistant will evaluate every matching climate entity behind that target.

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

You can also select different target types in one condition. For example, you can add a specific entity and an area as targets in the same condition to check 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 Condition passes if option controls how the results combine:

• Any (default): the condition passes if at least one of the targeted entities matches. For example, if you check three smoke sensors and only one of them detects smoke, the condition still passes. This is useful for questions like “is there smoke anywhere in the house?”
• All: the condition passes only when every targeted entity matches. For example, if you check the same three smoke sensors, the condition passes only once all three report cleared. This is useful for “is the entire house safe now?” checks, so your automation does not send an all-clear while one room still has a reading.

Good to know

• This condition passes when the thermostat is in any active HVAC mode: heat, cool, heat/cool, auto, dry, or fan only. It does not pass when the thermostat is off.
• Thermostats that are unavailable (unavailable) or have an unknown state (unknown) are skipped and do not count as on. With Any behavior, if all targeted thermostats are unavailable or have an unknown state, the condition fails. With All behavior, if all targeted thermostats are unavailable or have an unknown state, the condition passes.
• To gate an automation on a thermostat being off instead, use Thermostat is off.
• To check for a specific HVAC mode, use Thermostat is in HVAC mode.

Try it yourself

Ready to test this? Go to Settings > Automations & scenes, open an automation, and add this condition. Trigger the automation with and without the condition met, and watch whether it continues or stops.

More examples

Real scenarios where this condition gates an automation. Copy any example and adapt it to your setup.

Automation: boost heating when temperature drops

When the outdoor temperature drops below 18°C, increase the target temperature to help warm up faster, but only if the heating is already running. Prevents the automation from adjusting the thermostat if someone deliberately left it off.

• Trigger: Numeric state: Temperature below 18°C
• Condition: Thermostat is on
  • Target: Living room thermostat
• Action: Set thermostat target temperature

alias: "Boost heating when outdoor temperature drops"
triggers:
  - trigger: numeric_state
    entity_id: sensor.outdoor_temperature
    below: 18
conditions:
  - condition: climate.is_on
    target:
      entity_id: climate.living_room
actions:
  - action: climate.set_temperature
    target:
      entity_id: climate.living_room
    data:
      temperature: 22

Still stuck?

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

Related conditions

These conditions work well alongside this one:

• Thermostat is off: Tests if one or more thermostats are off.

• Thermostat is in HVAC mode: Tests if one or more thermostats are set to a specific HVAC mode.

• Thermostat is heating: Tests if one or more thermostats are heating.