Shelter · Living in Your Vehicle
Sleeping warm in your vehicle, safely.
Cold nights in a car are manageable. The warmth comes from layers, blankets, and your own body heat, not from a flame or an engine left running while you sleep. Four rules keep the air safe. The rest is staying dry.
Tonight's four rulesBy Dan Whelan, founder of New World Survival
Researched from government agencies, university extension services, and other published sources. See our sources
What this guide covers
Warm from the inside out, air you can trust.
This guide is for anyone spending cold nights in a car, truck, or van: people between homes, families who evacuated and are waiting it out, and car campers. By the end you will know the four carbon monoxide rules that matter in a vehicle, how to stay warm without running anything, how long a battery-powered blanket really lasts, and the early signs that the cold is winning.
Most of the danger on a cold night is quiet. Carbon monoxide (CO) is a gas with no color or smell, produced by engines and anything that burns fuel. CDC notes that people who are asleep can die from it before they ever notice symptoms.[1] That is why the rules below come first, and why they never bend.
This page does not cover winter driving or keeping a house warm during a power outage. Those live in our winter driving guide and heating during power outages.
The rules
Is it safe to heat a car overnight? Four rules.
Each rule comes straight from federal safety guidance. None of them depend on what kind of vehicle you have.
01
No flame while you sleep.
The Consumer Product Safety Commission is direct: never use fuel-burning portable heaters or lanterns while sleeping in enclosed areas such as tents, campers, and vehicles.[2] That includes propane heaters sold as safe for indoor use, butane stoves, candles, and charcoal.
A car holds very little air. Whatever a flame gives off has almost nowhere to go.
02
Never run the engine inside a garage.
CDC guidance: never run a car or truck inside a garage attached to a house, even with the garage door open.[1]
CDC also warns that with only an SUV's tailgate open, exhaust gets pulled into the vehicle.[1]
03
Clear the tailpipe before you start.
Snow, ice, mud, or a bag pressed against the exhaust can push carbon monoxide back into the cabin. CDC says a blocked tailpipe lets CO build up quickly inside the vehicle and poison anyone inside.[3] Check it every time, and check again if snow keeps falling.
CDC also recommends having a mechanic check the exhaust system every year, since a small leak can let CO build up inside the vehicle.[1]
04
Warm up in short sessions, awake.
Ready.gov's guidance for drivers stranded in winter is to run the engine for about 10 minutes per hour to run the heater and charge a phone, with a window opened slightly for fresh air.[4] That guidance is written for someone stuck in a storm, and it pairs with rule 03: the tailpipe has to be clear first.
For a regular night, use the engine to warm the cabin before bed, then turn it off and let your layers hold the heat. Do not fall asleep with the engine running.[1]
If you feel sick, get out first.
Headache, dizziness, weakness, nausea, vomiting, sleepiness, and confusion are the signs of carbon monoxide poisoning, and they are easy to mistake for the flu.[2] If you feel dizzy, light-headed, or sick to your stomach and suspect carbon monoxide, CDC says to seek medical attention promptly.[5]
Staying warm
How do you stay warm in a car without the engine?
Start with what you are wearing and what is under you. A parked car loses its heat quickly once the engine is off, so the goal is to hold your own warmth close, not to heat the whole cabin.
Dress in loose layers
CDC recommends several layers of loose-fitting clothing, a hat, a scarf or knit mask over the face, and mittens or gloves.[6] Loose layers trap warm air. Tight ones squeeze it out. Wear the hat to bed.
Stay dry, and change before you sleep
Hypothermia can happen above 40°F when a person is chilled from rain, sweat, or cold water.[6] After a long walk or a day of carrying things, put on a dry base layer and dry socks before you settle in. Keep that set in a sealed bag so it stays dry.
Put something between you and the seat
The seat and the floor pull heat out of your body all night. A folded blanket, a sleeping pad, or a camping mat underneath you matters as much as what is on top. A sleeping bag holds heat better than loose blankets because it closes around you.
Share the warmth
A partner, a child, or a dog under the same blankets adds real heat. Cheryl, who reviews this section, puts it simply below.
A simple sleep system
Keep insulation below you and dry layers around you.
The seat pulls heat away from you, so give the bottom and top of your sleeping space separate jobs. The materials can be simple; the dry, layered setup matters.
-
1
Under you
Seat or floor
Folded blanket, sleeping pad, or camping mat
This layer slows the heat loss to the seat and floor.
-
2
Around you
Dry, loose sleep clothes and a hat
Sleeping bag or layered covers
Keep a dry set ready before you settle in for the night.
Life with Scooby
"Just put more covers on. And Scooby keeps me pretty warm, too."
Cheryl's take. Cheryl's winter routine is simple: more covers, Scooby beside her, and the engine off. She avoids idling for long because it burns gas and wears on the motor. She tried an electric blanket on a small battery unit and it ran the battery down in about four hours, so she is saving for a bigger one.
Reviewed by Cheryl, who lives in her car with her dog Scooby.
Battery heat
How long will an electric blanket run on a battery?
A heated blanket on a portable power station makes no exhaust, which is why it is the one powered heat source worth considering for a car. Whether it lasts the night is simple math.
01
Read two numbers
The blanket's label lists its draw in watts. The power station lists its capacity in watt-hours (Wh). Output watts, the bigger number on the box, is a different thing: it is how much the station can deliver at once, not how long it lasts.
02
Divide
Watt-hours divided by watts gives hours. A 300 Wh station running a blanket that draws 50 watts on its setting tops out around 6 hours. Expect somewhat less, because some energy is lost converting battery power for a wall-style plug.
03
Stretch it
Warm the bed for an hour before sleep, then turn it down or off and let your layers hold the heat. A lower setting draws fewer watts. Check the manual for how much each setting draws.
Check the recall list first.
On September 17, 2026, CPSC announced the recall of about 195,000 JKMAX heated blankets and heating pads sold on Amazon, after 577 reports of the heating elements overheating, smoking, melting, or burning, including 53 burn injuries.[7] Before you buy or use a heated blanket, search for its brand on the CPSC recall list, and follow the manufacturer's instructions.
A battery power station is not a generator. Gas generators are a different machine with their own placement rules, covered in our generators guide. For choosing a station, see portable power stations and the power needs calculator.
Know the signs
What are the warning signs of hypothermia?
Hypothermia is a body temperature that has dropped too low. It affects the brain first, which is what makes it dangerous: a person may not realize it is happening.[6] CDC lists people who stay outdoors for long periods, including people without homes, among those at highest risk.
CDC warning signs in adults
- Shivering
- Exhaustion or feeling very tired
- Confusion
- Fumbling hands
- Memory loss
- Slurred speech
- Drowsiness
Do not ignore shivering. CDC calls it an important first sign that your body is losing heat, and says constant shivering means it is time to go inside.[8] A body temperature below 95°F is a medical emergency. Get medical attention immediately.[6]
If a night is getting colder than your layers can handle, it is fine to leave the car for a warm place. Call or text 211 and ask about warming centers or shelter beds near you. Our displacement guide covers shelters, ID, and getting help in more depth.
Common mistakes
What people get wrong on cold nights.
"An indoor-safe propane heater is fine in the car."
CPSC's guidance makes no exception: no fuel-burning portable heaters while sleeping in a vehicle.[2] Use layers and a battery-powered blanket instead.
"I'll leave it idling and crack a window."
A cracked window is part of the guidance for short, awake warm-up sessions, not a license to sleep with the engine on.[4] Snow can bury a tailpipe while you sleep.
"It's only 45 degrees. I don't need to worry."
Damp clothes change the math. Hypothermia can happen above 40°F when someone is chilled from rain or sweat.[6] Dry layers matter as much as thick ones.
"Any cheap heated blanket will do."
Some low-cost heated blankets sold online have been recalled for overheating.[7] Check the brand on the CPSC recall list before you rely on one every night.
Sources
- CDC. "Carbon Monoxide Poisoning Basics." Centers for Disease Control and Prevention. cdc.gov. Accessed 2026-11-02.
- CPSC. "Portable Heaters and Camping Equipment." U.S. Consumer Product Safety Commission. cpsc.gov. Accessed 2026-11-02.
- CDC. "Clear Snow from Tailpipes." Centers for Disease Control and Prevention. cdc.gov. Accessed 2026-11-02.
- Ready.gov. "Winter Weather." U.S. Department of Homeland Security. ready.gov. Accessed 2026-11-02.
- CDC. "CDC Offers Winter Safety Tips." Press release, February 17, 2021. archive.cdc.gov. Accessed 2026-11-02.
- CDC. "Preventing Hypothermia." Centers for Disease Control and Prevention. cdc.gov. Accessed 2026-11-02.
- CPSC. "JKMAX Recalls Heated Blankets and Heating Pads Due to Fire and Burn Hazards." Recall 26-778, September 17, 2026. cpsc.gov. Accessed 2026-11-02.
- CDC. "Safety Guidelines: During and After a Winter Storm." Centers for Disease Control and Prevention. cdc.gov. Accessed 2026-11-02.
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