Relative humidity crossed threshold

The Relative humidity crossed threshold trigger fires when a humidity reading crosses into a zone you define. A bathroom sensor crossing above 70% after a shower, a basement sensor dipping below 30% in a dry winter, a reading entering a target comfort range, or a reading escaping that range are all supported.

Use Relative humidity crossed threshold to automate ventilation when the air becomes too humid, alert you when conditions in a sensitive room drift out of range, or coordinate devices that respond to specific humidity 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 Relative humidity 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 humidity sensor is in (like your bathroom or basement). You can also select a device, a specific entity, or a label.
5. From the triggers shown for that target, select Relative humidity 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 percentage or use an input_number, number, or sensor entity as the threshold.
7. Under Trigger when (see Behavior), pick Each, First, or All to control how the trigger behaves when multiple entities are targeted.
8. 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.
9. 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 crossed threshold is referred to as humidity.crossed_threshold. A basic example looks like this:

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

This fires whenever the bedroom humidity sensor enters the comfort range (40% to 60%).

To fire when the reading leaves a comfort range (escapes above 60% or below 40%):

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

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.

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 humidity range is typically 40% to 60%. Use Outside range with those bounds to fire the moment conditions drift out of that comfort zone.
• Pair this trigger with Relative humidity changed if you also want to react to smaller fluctuations between crossings.
• 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: turn on the bathroom fan when it gets too humid

After a shower, bathroom humidity can climb fast. This automation turns on the bathroom fan the moment humidity crosses 70%.

• Trigger: Relative humidity crossed threshold
• Target: Bathroom humidity sensor
• Threshold type: Above 70%
• Trigger when: Each
• Action: Fan: Turn on

alias: "Ventilate bathroom on high humidity"
triggers:
  - trigger: humidity.crossed_threshold
    target:
      entity_id: sensor.bathroom_humidity
    options:
      threshold:
        type: above
        value:
          number: 70
actions:
  - action: fan.turn_on
    target:
      entity_id: fan.bathroom

Automation: alert when basement humidity goes out of range

Keep your basement at a healthy humidity level by sending a notification whenever the sensor crosses a level that may indicate a moisture problem.

• Trigger: Relative humidity crossed threshold
• Target: Basement humidity sensor
• Threshold type: Above 60%
• Trigger when: Each
• For at least: 00:10:00
• Action: Notifications: Send a notification via mobile_app_phone

alias: "Alert on basement humidity"
triggers:
  - trigger: humidity.crossed_threshold
    target:
      entity_id: sensor.basement_humidity
    options:
      threshold:
        type: above
        value:
          number: 60
      for: "00:10:00"
actions:
  - action: notify.mobile_app_phone
    data:
      message: "Basement humidity crossed 60%."

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 changed: Triggers after one or more relative humidity readings change.