This is a large enough synthetic fiber "watch cap".  It's big enough to cover my head and ears!  Those you get at W*l-M*rt and other big box stores are too small.

Two of these stuffed in your coat pockets and you are ready for some serious cold!

I keep some sweat pants and some other gear in my truck in winter so I can survive being stranded in the cold.

Carhartt quality. Mine is a lovely olive drab green that blends if you know what I  mean.