If your car breaks down or you get a flat tire in cold, snowy weather, you'll likely have concerns about how to keep safe.

The Occupational Safety and Health Administration has some guidance.

• If you’re stranded in a vehicle, stay in the vehicle. Do not leave the vehicle to search for assistance, unless help is visible within 100 yards. Remember, you could become disoriented or get lost in blowing or drifting snow.
• Call for emergency assistance, if needed. Notify your supervisor, a family member, or a friend of your situation.
• Display a “trouble” sign by hanging a brightly colored cloth on the vehicle’s radio antenna and raising the hood.
• Turn on the vehicle’s engine for about 10 minutes each hour, to run the heat and keep warm. While the vehicle is running, turn on the dome light as an additional signal to passersby.
• Be aware of the dangers of carbon monoxide poisoning. Keep the exhaust pipe clear of snow, and open a downwind window slightly for ventilation.
• To avoid frostbite and hypothermia, do minor exercises like clapping hands and moving legs to maintain good blood circulation. Try not to stay in one position for too long. By staying awake, you’ll be less vulnerable to cold-related health problems.
• Use blankets, newspapers, maps, and even the removable floor mats for added insulation from the cold. 
• Avoid overexertion since cold weather puts an added strain on the heart.