I understand what you’re asking. Did you ever figure it out? I’m trying to do it as seen here in mushroom template card.
Update: nevermind I managed to do it as shown here but using my own weather entity
{% if is_state("weather.climacell_hourly","clear-day") %} mdi:weather-sunny {% elif is_state("weather.climacell_hourly","sunny") %} mdi:weather-sunny {% elif is_state("weather.climacell_hourly","clear") %} mdi:weather-sunny {% elif is_state("weather.climacell_hourly","clear-night") %} mdi:weather-night {% elif is_state("weather.climacell_hourly","rainy") %} mdi:weather-rainy {% elif is_state("weather.climacell_hourly","pouring") %} mdi:weather-pouring {% elif is_state("weather.climacell_hourly","snow") %} mdi:weather-snowy {% elif is_state("weather.climacell_hourly","fog") %} mdi:weather-fog {% elif is_state("weather.climacell_hourly","sleet") %} mdi:weather-partly-snowy-rainy {% elif is_state("weather.climacell_hourly","wind") %} mdi:weather-windy {% elif is_state("weather.climacell_hourly","cloudy") %} mdi:weather-cloudy {% elif is_state("weather.climacell_hourly","partlycloudy") %} mdi:weather-partly-cloudy {% elif is_state("weather.climacell_hourly","partly-cloudy-night") %} mdi:weather-night-partly-cloudy {% elif is_state("weather.climacell_hourly","hail") %} mdi:weather-hail {% elif is_state("weather.climacell_hourly","lightning") %} mdi:weather-lightning {% elif is_state("weather.climacell_hourly","tstorm") %} mdi:weather-lightning-rainy {% endif %}
