How to access today's max and min temperatures via the Met.no weather integration?

I use the Met.no weather integration which I display in the normal card:

As well as the current temperature, this card displays today’s forecast max and min temperatures (highlighted in the screenshot). I want to access those in a helper but they do not seem to be attributes of the entity:

What is the easiest way to access those values?

You need to get Temperature and Templow from the forecast data. Hopefully the yaml below will point you in the right direction:

template:
  - trigger:
      - platform: homeassistant
        event: start
      - platform: time_pattern
        minutes: "/30"
    action:
      - service: weather.get_forecasts
        data:
          type: daily
        target:
          entity_id: weather.home   # <-- replace with your Met.no entity id
        response_variable: forecast_data
    sensor:
      - name: "Today Max Temp"
        unique_id: today_max_temp
        unit_of_measurement: "°C"
        state: "{{ forecast_data['weather.home'].forecast[0].temperature }}"
      - name: "Today Min Temp"
        unique_id: today_min_temp
        unit_of_measurement: "°C"
        state: "{{ forecast_data['weather.home'].forecast[0].templow }}"

Note: this simply uses the daily forecast, so you could get some odd readings due to the daily refresh boundaries. To get a more accurate value you can use the hourly forecast and filter for the hours left in the day.

Many thanks for that, just what I wanted. Works great.