Winter hat. I'm the oldest of the millennials, so I only wear my winter hat and flannel jacket when I'm outside in the COLD weather. Not in the warmth of a starbucks reading poetry.
My mom always called them "sipple caps". I did a MS Bing search and found that the Amish, Dutch and Germans commonly called them sipple caps. Very old school.
Other: watch cap used to be much more common than toque or toboggan.
I have two ragg wool stocking caps that I where when it's nasty out. One's older and more beat up. Used to wear them all the time but have more options now.
I have beanies in several colors & patterns that Mrs. CHS1971 crocheted. Fairly lightweight and worn frequently.
I have two fleece lined ball caps that get worn the most.
I own three Tilley hats. One is a winter wool hat with a 2 5/8" brim and a turn down ear flap. I wear it when I need something classier.
I have an inexpensive wool felt cowboy hat with an ear flap that I will wear in the late fall if I'm working in the yard and want something to keep the sun off my face and neck.
On the rare occasion I wear something on my head in the winter (usually just in the morning when snowblowing the driveway), I just call it a winter hat.