HA Blueprint to match color temperature of lights to the sun. To add it to your home assistant see it on the community forum: https://community.home-assistant.io/t/automatic-circadian-lighting-match-your-lights-color-temperature-to-the-sun/472105

match-color-temp-kelvin.yaml

blueprint:
  name: Match Outside Colour Temperature Kelvin
  description: When a light turns on or the sun elevation changes, match the outside
    colour temperature. It will apply to any bulb that supports color temperature.
    It triggers; whenever a bulb turns on, on sun elevation changes and every 5 minutes.
  domain: automation
  input:
    target_lights:
      name: Lights
      description: The primary lights to be controlled
      selector:
        entity:
          domain: light
          multiple: true
    min_color_temp:
      name: Coolest Color Temperature
      description: The most blue color your bulbs will be set to
      default: 4000
      selector:
        color_temp:
          min: 1500
          max: 7000
          unit: kelvin
    max_color_temp:
      name: Warmest Color Temperature
      description: The most yellow color your bulbs will be set to
      default: 2202
      selector:
        color_temp:
          min: 1500
          max: 7000
          unit: kelvin
    brightness_action:
      name: Brightness
      description: When a device turns on its color temperature will be set, this
        may interfere with the brightness, this action will run half a second later
        to set the light's brightness.
      selector:
        action: {}
      default:
      - service: light.turn_on
        data:
          brightness: '{{max(trigger.to_state.attributes.brightness,2)}}'
        target:
          entity_id: '{{trigger.entity_id}}'
        alias: Default - Set light to its original brightness, don't use brightness
          1 as it causes issues with some bulbs
  source_url: https://gist.github.com/HarvsG/cc86381dc99169159d6d4cd870c36e46
variables:
  target_lights: !input target_lights
  target_on_lights: '{{states.light | selectattr(''state'',''eq'',''on'') | selectattr(''attributes.supported_color_modes'',''match'',".*color_temp.*")
    | map(attribute=''entity_id'') | select("in",target_lights) | list }}'
  min_color_temp: !input min_color_temp
  max_color_temp: !input max_color_temp
  color_temp: '{{ [([(((4791.67 - 3290.66/(1 + 0.222 * ([([0,state_attr(''sun.sun'',
    ''elevation'')]|max),90]|min**0.81))))|int),max_color_temp]|max),min_color_temp]|min}}'
trigger:
- platform: state
  entity_id: !input target_lights
  to: 'on'
  id: single_light_on
- platform: state
  entity_id:
  - sun.sun
  attribute: elevation
  id: elevation_change
- platform: time_pattern
  minutes: '5'
  id: every_5_min
condition:
- condition: template
  value_template: '{{ (states.light | selectattr(''state'',''eq'',''on'') | map(attribute=''entity_id'')
    | list)!= [] }}'
action:
- choose:
  - conditions:
    - condition: trigger
      id: single_light_on
    sequence:
    - service: light.turn_on
      data:
        color_temp_kelvin: '{{color_temp}}'
      target:
        entity_id: '{{trigger.entity_id}}'
    - delay:
        milliseconds: 500
    - choose:
      default: !input brightness_action
  - conditions:
    - condition: or
      conditions:
      - condition: trigger
        id: every_5_min
      - condition: trigger
        id: elevation_change
    sequence:
    - service: light.turn_on
      data:
        color_temp_kelvin: '{{color_temp}}'
        transition: 5
      target:
        entity_id: '{{target_on_lights}}'
mode: parallel

Thanks a lot for sharing this work!

min_color_temp and max_color_temp should probably be named the other way around, since "the most blue" colour has a higher colour temperature. With the naming as is, this line is hard to digest:

color_temp: '{{ [([(((4791.67 - 3290.66/(1 + 0.222 * ([([0,state_attr(''sun.sun'', ''elevation'')]|max),90]|min**0.81))))|int),max_color_temp]|max),min_color_temp]|min}}'

[<calculation>, max_color_temp]|max would allow setting temperature to higher than max_color_temp, which doesn't make sense. The same for min.

Yes this is vestigial from when home assistant used Mireds which is the inverse of Kelvin.
It also results for the colour temperature paradox which is that high temperature whites are often described as 'cool' and low Kelvin temperature whites are described as 'warm'.

I'm getting this error with a recent version of home-assistant:

WARNING (MainThread) [homeassistant.components.light] Got `kelvin` argument in `turn_on` service, which is deprecated and will break in Home Assistant 2026.1, please use `color_temp_kelvin` argument

Sounds like the data: kelvin: needs to be changed to color_temp_kelvin?

Sounds like the data: kelvin: needs to be changed to color_temp_kelvin?

Thank you, I have done this now and it appears to be working

To update, click re-import blueprint:

Sounds like the data: kelvin: needs to be changed to color_temp_kelvin?

Thank you, I have done this now and it appears to be working

To update, click re-import blueprint:

Hi, I don't see color_temp_kelvin on the code above?

Sounds like the data: kelvin: needs to be changed to color_temp_kelvin?

Thank you, I have done this now and it appears to be working
To update, click re-import blueprint:

Hi, I don't see color_temp_kelvin on the code above?

Line 82 and 99

This is a great and simple. Some of the circadian lighting integrations seem overly complicated to me.

Is there a way to limit the timing of this? For example, don't turn on until 8am and turn off at 5pm. It wouldn't have to adjust the light color to those times at all, just not turn on unless its between those times.

Seems like a simple condition could be added. I'll work on it a little, but I'm pretty new to HA.

I'm not sure what you mean by "not turn on" this automation shouldn't turn on lights - only change the colour temperature of lights already on or that have just turned on.

If you mean you only want the automation to operate between the hours of 8am and 5pm then simply create another automation that disables and enables this automation at those times

Or you can "Take control" of this blueprint and change the logic to your delight https://www.home-assistant.io/docs/automation/using_blueprints/#editing-an-imported-blueprint