I recently went on the marketplace to look for a weather pack and i found one perfect for me, exactly what i wanted. I even went to his YouTube channel and there was a comment from three years ago saying that the weather layer was in development (of course, he or she could be mistaken) but the point is, why didn't they created it yet? I absolutely love Roll20, i use it since i joined, bought plus and then went to pro, and it saddens me that i can't put fog or rain in my map with either dragging the rain around or putting my players and monsters on top of it.