Why extremities go first

When the body gets cold it protects the core, narrowing the blood vessels at the skin and in the hands and feet. That is why fingers and ears go numb long before you feel cold through a torso layer.

What that means in practice

Adding a warmer jacket does not fix cold hands directly, but it does indirectly: a warm core means the body is less aggressive about shutting down circulation to the extremities.

Close the gaps

The collar, the wrists and the waist are where warm air leaves. A neck gaiter or balaclava, cuffs that actually grip, and a garment long enough to stay tucked make more difference than a heavier coat.

Watch for the warning signs

Numbness that does not come back after a warm-up break, or skin that stays white and firm, means stopping and warming up properly, not pushing through.