If you spend any time outside in conditions like these, it doesn't take long at all before frost bite can occur.
FYI, this was one of the least graphic images I could find of frostbite.
Chemical hand warmers; you've probably seen them, maybe you've even used them.
But keep reading because you've probably been using them wrong, or at least, inefficiently.
Most people who use these simply put them in their pockets, which works, if you' don't need to take your hands out of your pockets.
But, if you keep them held against the inside of your wrists, where the radial artery is close to the skin, you apply additional warmth where it's needed the most.
Image & wrist of @theblindsquirl
And, you can still use your hands.
These are called Crazy Thermal Bands and I bought them about 15 years ago.
Image by @theblindsquirl
The handwarmers fit into the fleece pouches and are secured to your wrists by a velcro strap.
Like most things that work, I can't find them anywhere now.
But, I've found a decent alternative.
It's also available on Amazon.
A simple way to think of body heat loss is to consider the heating system in your house.
The further away from the furnace or boiler (your core), the less heat there is available.
That's why the rooms furthest away from your heat source (or, your hands & feet) have the least amount of heat.
Adding supplemental heat where you need it most, frees up more energy for the core.
I have at least one set of these in each car, along with 5 pairs of the chemical handwarmers.
They work amazingly well.