Hand warmers. The chemical kind, not the burning kind.

One in each mitten and one in each boot. You will need to have mittens that block the wind and boots that have enough room to hold the hand warmer by the toes. Take a ziplock baggie with to hold them when you get to your destination. They generally last for 8-12 hours, with the zip lock I've had them last 3 days.

My hands and feet were always cold before doing this, it does not matter how much clothing I have on the rest of the body, the hands and feet get numbingly cold unless there is a heat source with them.