Home Assistant freeze alert template

freeze-alert-template-test.yaml

{# ============================
   MOCK DATA FOR TEMPLATE EDITOR
   Remove this whole block in the real automation
   ============================ #}
{% if not wx %}
{% set wx = {
  'weather.openweathermap_forecast': {
    'forecast': [
      {
        'datetime': '2025-11-07T13:00:00+00:00',
        'condition': 'sunny',
        'temperature': 13.6,
        'pressure': 1018,
        'cloud_coverage': 0,
        'wind_speed': 7.42,
        'wind_bearing': 94,
        'uv_index': 0.9,
        'precipitation_probability': 0,
        'precipitation': 0,
        'apparent_temperature': 12.4,
        'dew_point': 3.7,
        'wind_gust_speed': 9.76,
        'humidity': 51
      }
    ]
  },
  'weather.forecast_home': {
    'forecast': [
      {
        'datetime': '2025-11-07T13:00:00+00:00',
        'condition': 'sunny',
        'temperature': 14.3,
        'wind_bearing': 74.9,
        'cloud_coverage': 0,
        'uv_index': 0.7,
        'wind_speed': 7.9,
        'precipitation': 0,
        'humidity': 54
      }
    ]
  },
  'weather.home': {
    'forecast': [
      {
        'datetime': '2025-11-07T14:00:00+00:00',
        'condition': 'sunny',
        'temperature': -1,
        'precipitation': 0
      }
    ]
  }
} %}
{% endif %}

{# ============================
   REAL LOGIC (use this part in automation)
   ============================ #}
{% set start = today_at('18:00') %}
{% set end = today_at('06:00') + timedelta(days=1) %}
{% set ns = namespace(any_cold=false, matches=[]) %}

{% if wx is defined %}
  {# wx is a dict keyed by entity_id; each value has .forecast (list) #}
  {% for v in wx.values() %}
    {% for p in (v.forecast | default([])) %}
      {% set t = as_local(as_datetime(p.datetime)) %}
      {% set temp = (p.temperature | default(p.native_temperature)) %}
      {% if t >= start and t <= end and (temp | float(99)) <= 1 %}
        {% set ns.any_cold = true %}
        {# Safe reassignment instead of .append() #}
        {% set ns.matches = ns.matches + [{'t': t, 'temp': temp}] %}
      {% endif %}
    {% endfor %}
  {% endfor %}
{% endif %}

{# ===== Output for automation (boolean) ===== #}
{{ ns.any_cold }}

{# ===== Debug (visible only in Template Editor) ===== #}
{% if ns.matches | length == 0 %}
  {# No matches in the window #}
  {{ '\n' }}No forecast hours ≤ 1 °C between 18:00 and 06:00.
{% else %}
  {{ '\n' }}Matching hours (local time):
  {% for m in ns.matches %}
    - {{ m.t }} → {{ m.temp }} °C
  {% endfor %}
{% endif %}