While working on a map, I have come across an issue that adds snow in regions which are supposed to be of a temperate climate as they are not defined in climate.txt. This is the case both on desert wastelands and desert provinces. The snow stays during the entire year, and has a different texture from the normal snow. Has anyone else ever experienced this issue?
To visualise, this is the texture the snow has:
Terrain map
Political map
To visualise, this is the texture the snow has:

Terrain map

Political map