Hello, and thanks for writing in.
The white flakes on the skin can be due to dry skin, especially this time of year, just like we can get dry skin. There can also be more specific causes of the dry skin, such as parasites, ringworm, infections, endocrine disorders, to name a few. Ideally, this would be something to have your veterinarian look at so they can treat as appropriately as possible. But, there are a few things you can try at home for now.
You can bathe your dog in an oatmeal shampoo. You can also try getting a dog moisturizing shampoo and follow up with a dog hair coat conditioner. Run a humidifier in your home to decrease the dryness in the air. Don't use human shampoos on your dog - it will dry the skin even more. You can also supplement your dog's diet with a fatty acids supplement.
Here is a thorough article on fatty acids in dogs:
Here is a thorough article with an included table on causes of dry skin in dogs:
I hope this helps.