Humidifier started humidifying

The Humidifier started humidifying trigger fires when a humidifier 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] begins actively adding moisture to the air. A humidifier that is turned on does not necessarily humidify continuously. It pauses once the target humidity is reached and then resumes when the air dries out again. Humidifier started humidifying fires whenever it moved from idle back to active humidification.

Use Humidifier started humidifying to track active humidification cycles, send notifications when the air is dry enough that the device kicks back in, or coordinate other devices that should run alongside it.

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 Humidifier started humidifying 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 humidifier 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 Humidifier started humidifying.
6. Under Trigger when (see Behavior), pick Each, First, or All to control how the trigger behaves when multiple humidifiers are targeted.
7. Under For at least, set how long the humidifier must be actively humidifying before the trigger fires. Leave it at zero to fire immediately.
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, Humidifier started humidifying is referred to as humidifier.started_humidifying. A basic example looks like this:

trigger: humidifier.started_humidifying
target:
  entity_id: humidifier.bedroom

This fires every time humidifier.bedroom starts actively adding moisture to the air.

Options in YAML

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

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 humidifier entity behind that target.

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

• Humidifier started humidifying fires independently of Humidifier turned on. A humidifier can be on but idle, and Humidifier started humidifying fires only when it moves from idle to active.
• To react to the opposite transition on a dehumidifier, use Humidifier started drying.
• If your device is a dehumidifier, it removes moisture rather than adds it. Use Humidifier started drying instead.

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: notify when the nursery needs more moisture

When the nursery humidifier starts humidifying again after a pause, it means the air has dried out. Send a gentle notification so you’re aware the cycle has restarted overnight.

• Trigger: Humidifier started humidifying
• Target: Nursery humidifier
• Trigger when: Each
• Condition: Time is between 22:00 and 07:00
• Action: Send a mobile notification

alias: "Alert when nursery starts humidifying at night"
triggers:
  - trigger: humidifier.started_humidifying
    target:
      entity_id: humidifier.nursery
    options:
      behavior: any
      for: "00:00:00"
conditions:
  - condition: time
    after: "22:00:00"
    before: "07:00:00"
actions:
  - action: notify.mobile_app_phone
    data:
      message: "Nursery humidifier started humidifying."

Automation: turn on a fan to help distribute moisture

When the bedroom humidifier starts humidifying, turn on a low-speed fan to distribute the moisture more evenly throughout the room.

• Trigger: Humidifier started humidifying
• Target: Bedroom humidifier
• Trigger when: Each
• For at least: 00:00:00
• Action: Fan: Turn on

alias: "Run fan when bedroom humidifies"
triggers:
  - trigger: humidifier.started_humidifying
    target:
      entity_id: humidifier.bedroom
    options:
      behavior: any
      for: "00:00:00"
actions:
  - action: fan.turn_on
    target:
      entity_id: fan.bedroom
    data:
      percentage: 30

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:

• Humidifier turned on: Triggers after one or more humidifiers turn on.

• Humidifier started drying: Triggers after one or more humidifiers start actively drying (dehumidifying).