Polar night started

The Polar night started trigger fires when the polar night period begins, the part of the year at high latitudes when the sun stays below the horizon for a full 24 hours and stops rising. Home Assistant calculates this for your home location.

Use it to switch to a dark-season setup for the period ahead. For example, turn on a daylight lamp routine during the day, or send yourself a reminder that the sun will not rise for a while.

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 this trigger 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. From the search box, search for and select Polar night started.
5. Optionally, set an offset to fire before or after the polar night starts:
   • Under Offset, enter how far from the start of the polar night to fire, such as 1 day.
   • Under Offset type, select Before or After.
6. 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, refer to this trigger as sun.polar_night_started. A basic example looks like this:

trigger: sun.polar_night_started

This fires when the polar night period starts. To fire a fixed amount of time before or after it starts, add the offset and offset_type options:

trigger: sun.polar_night_started
options:
  offset:
    days: 1
  offset_type: before

This fires one day before the polar night starts.

Options in YAML

Good to know

• This trigger does not use a target. It applies to the sun at your configured home location.
• The polar night only happens at high latitudes, roughly above the polar circles. Elsewhere, this trigger never fires.
• The polar night starts when the sun’s daily high point, at solar noon, first stays below the horizon. From then until it ends, Sunrise and Sunset do not fire, though there can still be some twilight around midday.
• To react when the polar night period is over and the sun rises again, use Polar night ended.

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].

For this trigger, there is no target entity to change. Because the polar night happens at most once a year, test the automation by temporarily switching to a trigger you can control while you build the rest of it.

More examples

Real scenarios where this trigger fires in automations and scripts. Copy any example and adapt it to your setup.

Automation: remind you to prepare for dark days

When the polar night period starts, send a notification so you can get ready for the period without a sunrise.

• Trigger: Polar night started
• Action: Send a notification message
  • Target: My Device (notify.my_device)

alias: "Notify when the polar night starts"
triggers:
  - trigger: sun.polar_night_started
actions:
  - action: notify.send_message
    target:
      entity_id: notify.my_device
    data:
      message: >
        The polar night has started. The sun will not rise for a while.

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:

• Polar night ended: Triggers when the polar night period ends and the sun rises again.

• Midnight sun started: Triggers when the midnight sun period starts and the sun stops setting.

• Sunrise: Triggers when the sun rises.