Emergency blankets, water and supplies: what to carry if you get stranded in your car
Choose the right blankets, pack enough water and size your kit for every trip
Safety Behind the Wheel Foundation built this guide from National Weather Service winter storm guidance, Centers for Disease Control and Prevention (CDC) cold, water and carbon monoxide guidance, National Highway Traffic Safety Administration (NHTSA) and Occupational Safety and Health Administration (OSHA) winter lists, and published blanket research. Every source is listed at the end.
Why blankets and water matter when you are stuck
Most breakdown advice covers the first few minutes. This guide covers what comes next, when a storm, a wreck ahead or a remote road leaves you waiting for hours. Everyday drivers, families, fleets and remote travelers all need some version of this kit.
From 2019 to 2023, the United States averaged nearly 745,000 weather related crashes a year [6]. Those collisions killed more than 3,800 people and injured more than 268,000 each year on average [6]. About 18 percent of them happened in snow, sleet, hail or freezing rain [6]. One crash can close a road and strand many drivers.
If your car gets stuck in a winter storm, the National Weather Service says to stay in it [1]. Safety Behind the Wheel Foundation gives drivers the same advice. If you walk away in wind driven snow, you can quickly lose your sense of direction [1]. That makes your car a shelter, and a shelter is only as good as what is inside it.
NHTSA’s winter list includes blankets, water, food, any medicine you need, and a phone with a charger [7]. Build on that list by asking three questions. Who is riding with you? How cold or hot could it get? How long could help take? Lights, first aid kits, jump starters, traction aids and warning devices have their own Drive With Care guides.
How cold affects people waiting in a car
A stopped car cools fast once the engine is off. If you step outside, wind and wet clothes take heat even faster.
At 0°F with a 15 mph wind, the wind chill is -19°F, according to the National Weather Service [8]. At that wind chill, bare skin can freeze in 30 minutes [8].
Hypothermia is a dangerous drop in body temperature. The CDC says to get medical help right away if a person’s temperature is below 95°F [9]. Warning signs in adults include shivering, exhaustion, confusion, fumbling hands, memory loss, slurred speech and drowsiness [9]. A baby may have bright red, cold skin and very low energy [9].
Frostbite is an injury caused by freezing. It most often affects the nose, ears, cheeks, chin, fingers and toes [10]. Watch for white or grayish yellow skin, skin that feels firm or waxy, and numbness [10].
Your body is the heater. Blankets and clothing only hold in the heat it makes, and food and water keep it running. A good kit covers all three.
Choosing emergency blankets
A Swedish lab study tested 12 blankets and rescue bags used by ambulance and rescue crews [3]. The team measured them on a heated mannequin inside a climate controlled test room [3]. In still air, warmth mostly tracked with thickness [3]. Thin foil blankets did better than their thickness would suggest [3].
Wind changed the picture. In moderate and strong wind, light materials that let air through kept only about 30 to 50 percent of their insulation [3]. Windproof covers that did not flatten kept about 60 to 80 percent [3]. For long waits outdoors, the authors stressed a windproof outer layer that resists being pressed flat [3].
A second lab study used bags of warm fluid to stand in for a person’s torso [4]. Unlike a person, it made no heat of its own. At 68°F, a foil “space blanket” and a wool blanket did not stop heat loss beyond about 30 minutes [4]. The lesson is not that blankets fail. They slow cooling, but the heat must come from your body and short runs of the car heater.
Comparison compiled by Safety Behind the Wheel Foundation
Emergency blanket types compared
| Blanket type | Strengths | Limits |
|---|---|---|
| Foil emergency blanket (thin plastic sheet with a metal coating) | Tiny, light, blocks wind, holds in body heat | Tears easily, no padding. Best as an extra layer [3] |
| Wool blanket | Durable, warm, good to sit on | Heavy and bulky |
| Fleece or synthetic blanket | Light, dries fast, easy to wash | Wind passes through. Add a windproof layer [3] |
| Cold rated sleeping bag | Most warmth for long or remote waits | Takes space. Check the temperature rating |
Start with one warm fabric blanket or sleeping bag for every seat you fill. Then add one foil blanket per person as a backup. Pick sizes that cover an adult from shoulders to feet. For remote winter routes, a sleeping bag rated for the coldest weather you expect is worth the space.
Using blankets and layers the right way
If you are stuck in the cold, work through these steps:
- Get dry first. Change wet socks, gloves or layers before you wrap up, since damp clothing keeps pulling heat away.
- Cover your whole body, including your head, with extra clothing and blankets [2].
- Put insulation under you, too. Fold a blanket on the seat or under your feet to block the cold.
- Wrap a foil blanket over your fabric layers if you must step outside or the car is drafty.
- Move your arms and legs often while seated, and huddle with others for warmth [2].
- Stay awake if you can, since that makes you less likely to get sick from the cold [2].
Use chemical heat packs with care. In the fluid model study, the surface of every heat making device topped 111°F with long use [4]. The authors advised putting an insulating layer between the person and any active warmer [4]. Wrap heat packs in cloth and keep them off bare or numb skin. The CDC also warns against warming frostbitten skin with a heating pad or electric blanket, and against rubbing it [10].
If a child rides in a car seat, lay blankets over the buckled harness. Do not tuck them under the straps or behind the child.
Water: how much to carry and how to keep it usable
The CDC advises storing at least 1 gallon of water per person per day, for 3 days, at home [5]. It suggests storing more for pregnant women, sick people, pets, or anyone in a hot climate [5]. A commute does not need a three day supply, but the per day figure is a handy yardstick. Think about the longest wait your route could bring, then pack for it.
Heat raises water needs sharply. For moderate work in the heat lasting under 2 hours, NIOSH advises 1 cup (8 ounces) of water every 15 to 20 minutes [11]. If you might walk, dig or change a tire in summer heat, a gallon can go fast.
The CDC says to keep stored water between 50°F and 70°F, out of direct sunlight, and to follow the expiration date on store bought water [5]. A parked car is often much hotter or colder than that. So keep car water shaded and swap it out more often. If you fill your own containers, the CDC says to replace the water every 6 months [5].
In winter, water can freeze. Leave space at the top of refillable bottles, since water expands as it freezes. Keep a bottle or two in the cabin, and thaw frozen ones near a heater vent while the engine runs.
Do not eat snow. The CDC warns that it lowers your body temperature [2]. Some winter lists include a can for melting snow [12]. Never use an open flame inside a closed car. Melt snow in a bottle near the heater vent instead.
An insulated bottle of a warm drink is a smart winter extra. Warm drinks can help raise body temperature, but the CDC warns against alcohol [9].
Food, clothing, medicine and other essentials
Public safety lists overlap on the basics: blankets, water, snacks, medicine and extra warm clothing [7, 12, 13]. NIOSH tells outdoor workers to carry extra socks, gloves, a hat, a jacket, spare clothes and blankets [14]. Beyond blankets and water, pack:
- Food: high energy, no cook foods that keep, such as nuts, granola bars, crackers and dried fruit. Choose foods everyone in the car can safely eat.
- Dry clothing: a hat, mittens or gloves, thick socks, a warm layer and waterproof boots for each person [12, 14]. Keep them in a sealed bag so they stay dry.
- Medicine: a few days of any daily or rescue medicines, labeled. If the label says to avoid heat or freezing, keep them in a bag you carry in and out.
- Baby and child items: diapers, wipes, formula or baby food and a change of clothes.
- Pet supplies: extra water, a bowl, food, a leash and a towel or blanket [5].
- Sanitation: toilet paper, wipes, hand sanitizer and sealable bags.
- Power: a phone charging cord and a charged backup battery [7, 12].
- A signal: a brightly colored cloth to tie to the antenna or door, preferably red [1].
Size the kit for your passengers, climate and trip
One kit does not fit every trip. The water amounts below build on the CDC home yardstick of 1 gallon per person per day [5].
Comparison compiled by Safety Behind the Wheel Foundation
How to size the kit for your trip
| Trip type | Warmth | Water and food |
|---|---|---|
| Short winter trips in town | One blanket per seat, hats and gloves, foil blankets | A bottle or two per person, snack bars |
| Long winter highway drive | Blanket or sleeping bag per person, dry socks and layers | About 1 gallon per person, a day of snacks |
| Remote or mountain winter route | Cold rated sleeping bag per person, windproof outer layer | Several days of water per person, high calorie food |
| Hot or desert route | Sun cover, light layers, one blanket for cold nights | More than 1 gallon per person per day [5, 11] |
Then adjust for the people in your car:
- Pack extra layers for babies and older adults, who are among those most often hurt by cold [9].
- Add supplies for anyone with a medical condition, mobility needs or special diet.
- Add water and a blanket for each pet [5].
- Before a long or remote trip, tell someone your route and when you expect to arrive.
Fleets can use the same approach. OSHA’s winter list for work vehicles includes blankets, a change of clothes, snacks and water [13]. OSHA also says employers should set and enforce driver safety policies [13]. A simple step is a standard kit in every vehicle, sized to crew and route, and checked at each scheduled service.
While you wait: make your supplies last
Use heat carefully. Before you start the engine, dig any snow away from the exhaust pipe [1]. Run the engine and heater in short spells, about 10 minutes in every hour, with one window cracked open [2]. Recheck the pipe each time. Use those warm minutes to thaw water, warm hands and feet, and charge your phone.
Know the signs of carbon monoxide. Carbon monoxide (CO) is a gas in engine exhaust that you cannot see or smell. Common symptoms include headache, dizziness, weakness, upset stomach, vomiting, chest pain and confusion [15]. People who are asleep can die from it before they notice symptoms [15]. Take turns staying awake while the engine runs. If anyone feels ill, shut off the engine and let in fresh air.
Eat and drink a little at a time. Small, regular snacks and sips keep your body making heat.
Watch each other. Check often for shivering, confusion and pale, numb skin. Do not walk on frostbitten feet or toes [10]. Cold also strains the heart, so people with heart disease or high blood pressure should follow their doctor’s advice about shoveling [2]. For where to wait and how to call for help, see our roadside breakdown guide.
Where to get supplies and how to pack them
Auto parts stores sell foil blankets and basic roadside kits. Outdoor and camping stores carry wool blankets, sleeping bags and insulated bottles. Safety and medical suppliers sell foil blankets and heat packs in bulk for fleets. Grocery stores and pharmacies cover water and snacks.
Ready made kits are a fine start, but open the bag before you rely on one. A kit with a single foil sheet and one small water pouch will not cover a family. Add what is missing for your passengers and route.
Pack the kit so it stays useful and safe in a crash:
- Use a sturdy bag or bin, and tie it down in the trunk or cargo area so it cannot fly forward in a collision.
- Put blankets and clothes in sealed bags to keep them dry.
- Keep a small grab bag in the cabin with a foil blanket, hat, gloves, water, a snack and a phone cord, in case snow or damage blocks the trunk.
Check and refresh your kit
An easy habit is to tie the check to the spring and fall clock changes. Also check the kit after every use and before any long trip.
Frequently asked questions
Is a foil emergency blanket enough on its own?
Not for a long wait. In still air, thin foil blankets held heat better than their thickness suggested [3]. But in a model with no body heat, a space blanket did not stop heat loss beyond about 30 minutes [4]. Use foil as a light, windproof extra layer, paired with a fabric blanket, dry clothes and a hat.
How much water should I keep in my car?
Start with the CDC home yardstick of at least 1 gallon per person per day [5]. For short trips in town, a bottle or two each may do. For long drives, plan on about a gallon per person, and more for remote routes or hot weather. Add water for pets and for anyone who is pregnant or sick [5].
Is it safe to leave bottled water in a hot car?
The CDC says to store water between 50°F and 70°F, away from direct sunlight, and to follow the expiration date [5]. A car often runs much hotter than that in summer. Keep bottles shaded, such as in an insulated bag, and replace them after a hot summer.
Can I eat snow if I run out of water?
No. The CDC warns that eating snow lowers your body temperature [2]. If you must use snow, melt it first in a bottle near the heater vent while the engine runs, and never light a flame inside a closed car. Treat melted snow as a last resort.
The bottom line
Recommendation from Safety Behind the Wheel Foundation
Safety Behind the Wheel Foundation encourages every driver to stock the car with a warm blanket and water for each person before winter and before any remote trip. A stranded car can keep you safe for hours, but only if you stock it for the people inside. Pack one warm blanket per person, foil blankets as backups, and dry clothes, hats and gloves. Carry water and food sized to your trip, your climate and your passengers.
Then keep the kit fresh with a twice a year check. If you do get stuck, stay with the car, keep the exhaust pipe clear and use heat in short bursts. Your supplies buy time for help to reach you.
Related articles
- Roadside breakdown safety: what to do when your car breaks down
- Driving in snow and ice: grip, black ice, skids and when to stay home
- Rural road safety: why country roads are deadlier and how to drive them
- Journey management for work drivers: weather, breakdowns and check ins
- Secure cargo and tow safely: a loading guide for families and trailers
Sources and further reading
- 1National Weather Service (NOAA). What To Do If You’re Caught in a Winter Storm. Accessed October 2026. weather.gov/safety/winter-during
- 2Centers for Disease Control and Prevention. Safety Guidelines: During and After a Winter Storm. Updated January 26, 2026. cdc.gov/…/stay-safe-during-after-a-winter-storm-…
- 3Henriksson O, Lundgren JP, Kuklane K, Holmér I, Bjornstig U. Protection against cold in prehospital care: thermal insulation properties of blankets and rescue bags in different wind conditions. Prehospital and Disaster Medicine 24(5):408-15. Published 2009. [https://pubmed.ncbi.nlm.nih.gov/20066643/](https://pubmed.ncbi.nlm.nih.gov/20066643/) (DOI: [https://doi.org/10.1017/s1049023x00007238](https://doi.org/10.1017/s1049023x00007238)) doi.org/10.1017/s1049023x00007238
- 4Dvir E, Epstein D, Berzon B, Raz A, Lehavi A. Differences in the thermal properties and surface temperature of prehospital antihypothermia devices: an in vitro study. Emergency Medicine Journal 39(11):833-838. Published online November 2021. [https://pubmed.ncbi.nlm.nih.gov/34740889/](https://pubmed.ncbi.nlm.nih.gov/34740889/) (DOI: [https://doi.org/10.1136/emermed-2020-211057](https://doi.org/10.1136/emermed-2020-211057)) doi.org/10.1136/emermed-2020-211057
- 5Centers for Disease Control and Prevention. How to Create an Emergency Water Supply. Updated June 27, 2025. cdc.gov/…/how-to-create-and-store-an-emergency-w…
- 6Federal Highway Administration, Road Weather Management Program. How Do Weather Events Affect Roads? Accessed October 2026. Data year: 2019 to 2023 (five-year annual averages). ops.fhwa.dot.gov/weather/q1_roadimpact.htm
- 7National Highway Traffic Safety Administration. Winter Weather Driving Tips: Prepare Your Vehicle. Accessed October 2026. nhtsa.gov/winter-driving-tips
- 8National Weather Service (NOAA). Understanding Wind Chill (wind chill chart). Accessed October 2026. weather.gov/safety/cold-wind-chill-chart
- 9Centers for Disease Control and Prevention. Preventing Hypothermia. Updated January 30, 2024. cdc.gov/winter-weather/prevention/index.html
- 10Centers for Disease Control and Prevention. Preventing Frostbite. Updated August 25, 2026. cdc.gov/…/preventing-frostbite.html
- 11CDC National Institute for Occupational Safety and Health (NIOSH). Workplace Recommendations: Heat Stress. Updated July 16, 2026. cdc.gov/…/index.html
- 12Centers for Disease Control and Prevention. Preparing for a Winter Storm. Updated December 2, 2025. cdc.gov/winter-weather/safety/index.html
- 13Occupational Safety and Health Administration. Winter Weather: Hazards and Precautions. Accessed October 2026. osha.gov/winter-weather/hazards
- 14CDC National Institute for Occupational Safety and Health (NIOSH). Cold and Work: Types, Causes, Preparation. Updated July 14, 2026. cdc.gov/niosh/cold-stress/about/index.html
- 15Centers for Disease Control and Prevention. Carbon Monoxide Poisoning Basics. Updated January 12, 2026. cdc.gov/carbon-monoxide/about/index.html
This article reflects the safety priorities of winter and remote travel preparedness for drivers and passengers. It is general safety education, not medical, legal or insurance advice. Guidance changes, so verify details with official sources. Supply needs vary with your health, passengers, vehicle and route. For medicine storage or health needs, ask your doctor or pharmacist. For road and weather conditions, check your state department of transportation and the National Weather Service before you leave. In an emergency, call 911. Reviewed October 2026.
Cite this article: Safety Behind the Wheel Foundation. “Emergency blankets, water and supplies: what to carry if you get stranded in your car.” drivewithcare.org, https://drivewithcare.org/emergency-blankets-water-car-supplies/. Reviewed October 2026.
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