What fabric are the warmest clothes made out of?

wool. leather. Natural textures tend to be warmer although some fabrics like boots are made out of "NASA" intelligence. Whatever that means.

Wool, and surprisingly, silk. Polyester is also very warm and some varieties are used in outdoor gear and repel water.

Flesh

Fur: with an inner layer facing inwards. I know- not a fabric.

My down coat has never disappointed.

Warm sunshine. Only.

Wool for sure!

Wool

No clue

Wool

Fleece

Wool

silk

Wool