What's causing this?

It’s raining cat and dogs here and the summary image is correct but the main screen icon is showing partly cloudy. Why?

Here’s another example:

i would say its becuase its linked to the mostly cloudy in the metar (i.e you have the metar updating the main screen icon)
or something like that…and or you have allocated your own icon, and its using that…but that icon should be a mostly cloudy instead of a partly cloudy one…i.e something along those lines