Winter time is usually NOT the time people think of getting portraits taken, especially in the Northern States and other countries. Why? Because its cold out, even snow covered.
However, this is actually a good time to get those portraits that are, "just a little bit different" than others. Maybe its even a time to get your next years Christmas Card photo done. It's also a good time because photographers usually have a lot less bookings and are more willing to offer discounts or are open to negotiating a bit more.
Winter time also offers unique scene's such as snow and ice that aren't often used in formal portraits. There is also a lot of room for creative expression, by both the subject and the photographer.
So go ahead and try to get your 2021 Christmas cards done now, ask a photographer for a mini session, or an "extreme temperature" discount. In any event, Winter is a good time for photo's.