Template Target?

Configuration
2

Try:

  - alias: "Window - Announce upstairs window open when about to rain"
    trigger:
    - platform: state
      entity_id:  group.upstairs_windows
      to: 'on'
    - platform: template
      value_template: "{{ 'rain' in states.sensor.dark_sky_summary.state }}"
    condition:
    - condition: and
      conditions:
        - condition: state
          entity_id: group.upstairs_windows
          state: 'on'
        - condition: template
          value_template: "{{ 'rain' in states.sensor.dark_sky_summary.state }}"
        - condition: time
          after: '6:00:00'
          before: '23:00:00'
    action:
      - service: notify.alexa_media
        data_template:
          target: >
            {% set hr = now().hour %}
            {% if hr < 10 %} group.all_echos_but_the_bedroom
            {% elif hr < 21 %} group.all_echos
            {% else } group.downstairs_echos
            {% endif %}
          data:
            type: announce
          message: "An Upstairs Window is currently open and it is about to rain."