With met.no weather feed to Home Assistant - there's no difference in night time weather and daytime - specifically a clear night and partly clear night.
A Clear sky is classed as a "sunny" state, even at night. I have added some checks in the HA yaml template to check if the Sun sensor (You need Sun in your Home Assistant install) is state = "below_horizon" and update "sunny" and "partlycloudy" to be "night" and "night-partly-cloudy". This then requests icons in the ESPHome yaml to include the Moon - which makes it look right when you are looking at the display at night, or when the upcoming forecast hours are night time - a clear night sky = the Moon, not the Sun.
Or at least it makes more sense in my eyes to see the Moon icons at night that seeing a clear Sunny day predicted for 2AM(!!) :)
Stephen Ludgate
Madelena Mak