Relative humidity changed

The Relative humidity changed trigger fires after a humidity reading changes. Humidity creeps up slowly in a bathroom after a shower, climbs in a greenhouse overnight, or drops when the sun beats down on a dry afternoon. Use the threshold type to filter which changes matter to your automation.

The threshold type controls where the new reading must land for the trigger to fire. You can require the new value to be above a level, below a level, within a range, or outside a range. You can also select Any change to fire on any change at all.

Use Relative humidity changed to log humidity trends, trigger a fan when the air in a room becomes noticeably more humid, 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 Relative humidity 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 humidity sensor is in (like your bathroom or bedroom). You can also select a device, a specific entity, or a label. When you target multiple entities (via area, label, or multiple entity selections), the trigger fires whenever any of them changes.
5. From the triggers shown for that target, select Relative humidity 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 percentage (0-100%), 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. 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, Relative humidity changed is referred to as humidity.changed. A basic example looks like this:

trigger: humidity.changed
target:
  entity_id: sensor.bedroom_humidity
options:
  threshold:
    type: above
    value:
      number: 5

This fires whenever the bedroom humidity sensor reading moves to a value above 5%. 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: humidity.changed
target:
  entity_id:
    - sensor.bedroom_humidity
    - sensor.bathroom_humidity
options:
  threshold:
    type: between
    value_min:
      number: 40
    value_max:
      number: 60

This fires whenever any of the humidity sensors changes to a value within the comfort range (40-60%).

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

trigger: humidity.changed
target:
  entity_id: sensor.bedroom_humidity
options:
  threshold:
    type: outside
    value_min:
      number: 40
    value_max:
      number: 60

To use a number helper as a dynamic threshold that you can adjust without editing the automation:

trigger: humidity.changed
target:
  entity_id: sensor.bedroom_humidity
options:
  threshold:
    type: above
    value:
      entity: input_number.humidity_alert_threshold

To monitor all humidity sensors in an area and trigger when any changes outside the comfort range:

trigger: humidity.changed
target:
  area_id: basement
options:
  threshold:
    type: outside
    value_min:
      number: 40
    value_max:
      number: 60

This fires whenever any humidity sensor in the basement area changes to a value outside the 40-60% range.

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 humidity entity behind that target.

• Entity: one specific humidity entity, such as humidity.living_room.
• Device: every humidity entity that belongs to a device.
• Area: every humidity entity in a room or area.
• Floor: every humidity entity on a floor.
• Label: every humidity 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 humidity first crosses a specific level, use Relative humidity crossed threshold instead.
• Pair this trigger with Relative humidity in follow-up conditions to verify the reading meets a threshold before continuing the automation.
• The trigger works with climate entities, humidifier entities, weather entities, and sensors with the humidity device class.

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: run the bathroom fan after a shower

After a shower, humidity in a bathroom can spike quickly. This automation turns on the bathroom fan whenever either bathroom humidity sensor rises above 70%, keeping the room from getting damp.

• Trigger: Relative humidity changed
  • Target: Bathroom and shower humidity sensors
  • Threshold type: Above 70%
• Action: Turn on fan
  • Target: fan.bathroom

alias: "Run bathroom fan on humidity spike"
triggers:
  - trigger: humidity.changed
    target:
      entity_id:
        - sensor.bathroom_humidity
        - sensor.shower_humidity
    options:
      threshold:
        type: above
        value:
          number: 70
actions:
  - action: fan.turn_on
    target:
      entity_id: fan.bathroom

Automation: log humidity changes in the greenhouse

Track how much the humidity in your greenhouse shifts throughout the day by sending a notification whenever the reading changes.

• Trigger: Relative humidity changed
  • Target: Greenhouse humidity sensor
  • Threshold type: Any change
• Action: Send a notification
  • Target: notify.mobile_app_phone

alias: "Log greenhouse humidity changes"
triggers:
  - trigger: humidity.changed
    target:
      entity_id: sensor.greenhouse_humidity
    options:
      threshold:
        type: any
actions:
  - action: notify.send_message
    target:
      entity_id: notify.mobile_app_phone
    data:
      message: "Greenhouse humidity changed significantly."

Automation: alert when humidity changes above comfort level

Send a notification whenever the bedroom humidity changes to a level above your personal comfort threshold. Use a number helper as the threshold so you can easily adjust your preferred level through the UI.

• Trigger: Relative humidity changed
  • Target: Bedroom humidity sensor
  • Threshold type: Above (entity: comfort humidity threshold)
• Action: Send a notification
  • Target: notify.mobile_app_phone

alias: "Alert when humidity changes above comfort level"
triggers:
  - trigger: humidity.changed
    target:
      entity_id: sensor.bedroom_humidity
    options:
      threshold:
        type: above
        value:
          entity: input_number.comfort_humidity_threshold
actions:
  - action: notify.send_message
    target:
      entity_id: notify.mobile_app_phone
    data:
      message: >-
        Bedroom humidity is now {{ trigger.to_state.state }}%, above
        your comfort threshold.

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:

• Relative humidity crossed threshold: Triggers after one or more relative humidity readings cross a threshold.