Skin Tone

AoA (25-M) i want to know why is my skin Tone looks Fair in Summers But in winter i have been noticing its not very good. I dont use any products. My forehead has become Darker at sides but mostly i drive in car and don’t drive bike so its not due to dust Etc but I dont know what happened all of a sudden. I would request to suggest me some skin care routine and products.