A quick search in the game files reveals some snowy terrain textures:
Textures\Terrain\TR_SnowDirty_A_DM.dds
Textures\Terrain\TR_SnowGrass_A_DM.dds
Textures\Terrain\TR_SnowHumpy_A_DM.dds
Textures\Terrain\TR_SnowMud_A_DM.dds
Textures\Terrain\TR_SnowPatches_A_DM.dds
... so I'd say that snowy terrain/tiles are in.
