Natural Warmth at the Neck
Wool insulates by trapping air within its crimped fibres, delivering warmth well out of proportion to its weight. Wrapped at the throat it closes the gap a coat collar leaves open, which is the single most effective way to feel warmer without wearing more layers.
It also handles moisture well, absorbing humidity without feeling damp against the skin, and it breathes, so a wool scarf stays comfortable when you move indoors rather than becoming stifling.