Keep Kids WARM AND SAFE in the Car Seat

Posted in: Blog, How to Keep Your Kids Happy (and safe), Tips & Tricks

We’ve got lots of suggestions below for ways to keep kids warm AND safe, but please read this first!

What difference does 4 inches make?

The average puffy coat/snowsuit adds about 4 inches of slack into the child’s harness straps. Why should you should care about 4 inches…

You’d care if you wear a size 32 pants and instead had to go to work in a size 36 without a belt.

You’d care if you had to put your newborn into size 5 diapers overnight.

You’d care if you had to walk your dog in a collar that was 4 inches too loose at the neck.

Warm and Safe w L 12.15.002We put the same baby, in the same car seat, wearing the same few thin layers of clothes underneath – but changed which jacket/bunting she was wearing. In all four winter outfits we tightened the straps all the way (as shown here) – so there was only one finger’s worth of room at her collarbone, and you couldn’t pinch any slack at the collarbone. With 2 of the 4 winter outfits, her straps were just as snug with or without the outerwear. But with the other 2 we were deceived – as we had to loosen the straps by 4 inches to fit the bunting/snowsuit!

What’s 4 inches to your child in a crash? A whole lot, says Miriam Manary of the University of Michigan Transportation Research Institute (UMTRI) – as 4 inches significantly increases the risk of injury, and particularly head injury. Here’s how she studied this (the video below uses her crash test footage):

In her crash test lab she properly installed 2 identical car seats side by side on the crash test sled bench. The only thing she varied was the snugness of the harness straps. She buckled one dummy properly, but the other dummy’s straps she left with 4 inches of extra slack.

The loose dummy’s head moved 4.25 inches farther forward than the properly buckled dummy. 4.25 inches is easily the difference between your child’s head hitting the back of the seat in front of them, or not, something which is a known cause of serious head injuries to real kids in real crashes. Not only was the head more likely to hit the back of the front seat, but the head was likely to strike the back of the front seat at a much lower point on the vehicle seat… a point that is often outside of the zone that is required to be padded to reduce the risk of head injuries.

The head and chest injury scores – which indicate how likely a real child would be to suffer a head or chest injury – were also significantly higher in the looser dummy because when the child is loose they can’t take as much advantage of the safety features that the car offers (like crumpling to absorb some of the force of the crash) to reduce injury to the people in the car.

If there is ever a place to dot your I’s and cross your T’s, your child’s car seat is certainly the place–it could literally save your child’s life. Car seat manufacturers and safety advocates warn that winter coats, snowsuits, buntings, sleeping bag inserts, head & body inserts you buy separately from the car seat, and other “fluff” are not safe in the car seat. In a nutshell, you end up holding the child’s body + fluff in the harness straps, and in a crash all the fluff compresses and the straps are too loose for the child’s body, which causes injuries. Besides the safety issue, winter coats and snowsuits make kids overheat in the car… and there’s no better way to piss a kid off than to overheat them while they’re strapped down. For a detailed explanation of why fluff is dangerous in the car seat, see here.

OK… so how do I keep my child both warm and safe in the car seat during winter?

The most important part happens before you even go out to the car!

Step 1:

Purchase coats & jackets with the car seat in mind AND dress your child in layers before strapping him into his car seat.

Warm and Safe w L 12.15.001Dress your child in 2 to 4 thin, tight layers. How many layers to use will depend on how cold it is outside, if you can warm your car up ahead of time, and how cold/warm your child tends to be on average. The goal is that your child is comfortable in the car – not too cold and not overheating.

Layers: Long sleeve onesies/undershirts and tights/leggings/long johns make a great base layer for babies and older kids. For kids in diapers, leg warmers may be easier than tights/leggings when it comes to diaper changes – BUT if you have a child who loves pulling his shoes & socks off, tights are a great way to keep your little Houdini’s feet warm.

Wearing Columbia Steens MT fleece jacket while sleeping in Clek Foonf

Wearing Columbia Steens MT fleece jacket while sleeping in Clek Foonf

Fleece: Fleece makes a great top layer – just make sure the jacket is thin & tight – otherwise you’ll have lots of fabric bunching up under the chest straps which isn’t safe. We love these Columbia fleece jackets – Steen Mt II for boys and Benton Springs for girls – available in infant, toddler, andkids sizes, they are typically under $30 and are great for the car seat (and for layering under another jacket when out on the playground in winter). They are snug fitting and survived a full winter of washings and look like new. The Columbia Snowtop II Bunting also works well (so long as you don’t get it 2 sizes too big). The NorthFace Infant OSO one piece is also car seat safe (again, so long as it is the proper size for the baby).

Super Thin Down: Some of the REALLY thin down jackets will also work so long as they are thin AND properly sized for your child. We tried these OneKid Packable Down Lightweight Puffers (girls and boys) and found them to be safe for the car seat when worn in the appropriate size for the child.

Car Seat Safe Winter Coats: There’s a new down winter coat that is car seat safe that we think is really great for parents who don’t want to deal with taking bulky winter coats on/off – it’s the OneKid Road Coat. There’s also the Cozywoggle – which is very warm and half the price of the OneKid Road Coat – but we personally find the Cozywoggle to be difficult to use in the car seat, particularly when trying to buckle a less-than-cooperative child. See below in our toddler & big kid section for more info on both of these coats.

3-in-1 jackets: 3-in-1’s that feature a removable fleece insert are great for the car – since you can unzip the outer layer, remove it, and leave the fleece on under the straps. The outer jacket can be used over top of the straps (the child can use it as a blanket, or put their arms in the sleeves so it is worn backwards).

Please note that jacket also needs to be short – as if it is longer than to the hips it will definitely be too bulky for the car seat.

If you have a jacket or thin snowsuit that you are wondering whether it’s thin enough to be safe in the car seat, watch these videos:

Step 2:

Buckle the child and get the straps snug.

Step 3: 

Cover the child OVER the straps in a way that allows them to be warm without overheating in the car and then stay warm when they go back outside into the cold.

Suggestions for Keeping Warm, By Age Range


Swaddle Twice

It’s safe to swaddle babies OVER the straps (never swaddle under the car seat straps). Use a thin receiving blanket first, then add a heavier blanket. Swaddling both warms and soothes babies. See this video for a how-to on car seat-safe swaddling.

Note: as the car warms up, you will want to remove the heavier blanket so your child does not overheat.

Swaddle + Bunting (that’s safe for the car seat!)

DSC_0242 L in Nido

7AM Enfant Nido

At first glance, the 7A.M. Enfant Nido might not look safe for the car seat… but it absolutely is safe as it has a large oval hole in back that allows you to put the product on AFTER the baby is buckled snug. It will work in infant and convertible seats.

There are just 2 thin layers of fabric behind the head – so you shouldn’t have to worry about this pushing your baby’s head down into a chin to chest position like other products can do. Even if planning to use it for a newborn, we suggest getting the large size – and recommend the quilted version as it is warmer than the all fleece version. The Nido also works if you are wearing the baby facing out in a soft carrier (like an Ergo 360, or Lillebaby Complete).

Shower Cap Style Covers

Called shower cap style as they have an elastic rim, these are covers that just go over the top of the car seat (with nothing under the straps or under the baby) and help keep the air surrounding the child warmer. They may also help keep people’s hands away from the baby when you’re around others. You’ll still likely want to use blankets on top of the child (under the shower cap cover) if it is really cold out.

Car Seat covers that ALSO work for babywearing (Ergo, Bjorn, Lillebaby, Beco, etc)

Wait… sleeping bags, like the Bundle Me, aren’t safe to use in the car seat?

Sleeping bags, like the Bundle Me, have a layer of fluff that goes UNDER the baby’s body… which is exactly where you do NOT want to add fluff. Because these sleeping bags are sold separately from the car seat, they have no safety standards they are required to meet, are not required to undergo any crash testing on your child’s particular car seat, and most importantly their use is strictly prohibited by most car seat manufacturers.

In the picture below, the fist worth of room that you find with the sleeping bag removed is exactly what the straps would feel like in the instant of a crash when the sleeping bag is in use. The crash forces will compress all the fluff in the sleeping bag, making it as if the sleeping bag didn’t even exist, and the straps therefore way too loose for the baby’s body.

If you have a sleeping bag and would like to use it in the car seat, you can cut it to remove the fabric behind the child’s back and under the bottom, leaving behind a safe product as shown in this video. Please note that if you cut the product, you’ll need to sew the cut edges. Otherwise there will be filler material coming out, and that’s a choking hazard for the child.

*If you have a car seat made by TOMY/Lamaze/The First Years, the use of the Bundle Me is allowed in some of their car seats as the companies are owned by the same parent company.

There are some sleeping bags – like the 7 A.M. Enfant ones shown in the picture below – that are designed to allow you to use a part of them safely in the car seat. With these, you leave the bottom part of the sleeping bag in the stroller, and you zip the top part off to use on the car seat. The top part is specially designed with a fleece sleeve at the bottom that fits over the foot area of the car seat. Another way you can use the top part is to tuck the baby’s feet into the fleece sleeve and use the top part more as a bunting for the child (again, all the fluff is over the straps in this scenario – making it safe for the car).

Note: Just the top part of these products are safe to use in the car seat (despite what some of the marketing images on the company website may show). The bottom part, while not safe for the car seat, is absolutely safe to use in the stroller as strollers don’t get into crashes.


Choose a Winter Coat that is Car Seat Safe

OneKid Road Coat: The OneKid Road Coat is a down jacket that is warm enough to be your child’s winter coat (rated to -10 Fahrenheit) – and also safe AND easy to be worn in the car seat due to an innovative design unlike other coats. It will be available in sizes 12M and 18M in October – and is available now in sizes 2 and up. We think this is a FABULOUS option for parents who don’t want to deal with taking coats on and off and those for whom the car will be cold for the first few minutes of the trip (not everyone has a remote starter…).

onekid road coat 6 pic image.001

CozywoggleThe Cozywoggle is a heavy winter coat that’s safe for the car seat. It opens in a unique way–it unzips from hip to wrist on both sides–which allows the harness straps to go under the coat. The coat becomes like a poncho when worn in the car seat. However, your child’s arms may be cold until the car warms up since the sleeves are either completely unzipped, or partially unzipped (you can re-zip to the elbow). The coat is well made and very warm for the child when worn outside the car (it is fleece lined in the torso part).

We understand there is a learning curve with using this product. We had some difficulty buckling the child, especially when the child was squirming, as the front of the coat hid the straps and buckles from view.

Screen Shot 2016-09-06 at 4.05.14 PM

Wear the Coat OVER the Straps
Have the child put her winter coat on backwards, over top of the harness straps (this will allow her to pull the coat off when the car warms up sufficiently.)

Unzip the Coat and Close it OVER the Straps
This is perfect for thin coats, because it gets rid of half of the fluff AND if the child gets warm during the car ride, they can unzip the coat to cool off a little. With bulky coats it’s still best to remove the coat completely (but, if you can’t/won’t remove the coat completely, this is a way to at least eliminate half of the fluff of the coat… which makes even the bulkiest of coats safer for the car seat).


Car Seat Poncho
These hooded ponchos are made of 2 layers of thick fleece. They’re durable and wear well (many use them for multiple kids).

7 A.M. Enfant Easy Cover

7 A.M. Enfant Easy Cover

7 A.M. Enfant Easy Cover

This is a super deluxe, super warm blanket with sleeves (think Slanket) that can be used in the car seat, or stroller, or while wearing your baby facing out, or while watching movies in the house, or any other time you want a blanket AND your hands free. The bottom can snap up to keep legs and feet warm.

Bonchos Blanket

Bonchos blanket

Bonchos blanket

A blanket with a comfortable neck hole AND holes for the hands… allowing your child to stay covered but have their hands free for playing. Also works in strollers and on baby carriers (facing out). They have ones that are single layers, and ones where there are 2 layers of fabric (and will do custom orders). Works for babies and big kids up to about age 3.

Good old fashioned blankets
Keep them in the car to use to cover the child. If it’s really cold (and you want to give the child a treat), put the blanket in the dryer for a few minutes to get it toasty before bringing it out to the car. It’s also a good idea to keep a few warm blankets in the car in case the car breaks down and you’re stuck.  You want to be able to keep your child and yourself warm as you wait for help.


Statements from the Car Seat Manufacturers Regarding “Fluff” and Other Extras

Baby Trend

Do Not dress your child in bulky clothing or other garments that will hinder the harness from being snug around your baby and properly latched between your child’s legs.

Accessory products for use with the Safety Seat are acceptable for use provided that they do not interfere with the harness assembly, or the proper adjustment of the harness such that it remains tight on the child’s shoulders at all times. Thick, soft, or other compressible material in excess of 1/4 inch thick should not be placed behind or under the child or between the child and harness straps. Examples of accessory products are head support pillows or rolled blankets to add additional head support.


The use of non-Britax Child Safety, Inc. covers, inserts, toys, accessories, or tightening devices is not approved by Britax. Their use could cause this restraint to fail Federal Safety Standards or perform worse in a crash. Their use automatically voids the Britax warranty.


NEVER use clothing or blankets that interfere with fastening or tightening the harness. An unsecured child could be ejected in a sudden stop or crash! To keep child warm, place a blanket over child and restraint AFTER you have properly secured child in harness.

DO NOT use any accessories, pads or products supplied by other manufacturers with this Child Restraint. Items not tested with this restraint could injure your child.


Child must be dressed in clothing with arms and legs that will not interfere with buckling and snugly adjusting harness. Never place blankets between harness and child.


Child must be dressed in clothing with arms and legs that will not interfere with buckling and snugly adjusting harness.

Do not use accessories or parts other than those provided by Combi USA. Use of accessories or parts from other manufacturers could alter the performance of the car seat.


Never secure child in infant carrier dressed in a bulky garment or heavy clothing.


Using any non-Diono/Sunshine Kids product with this restraint; or any product not specifically approved by Diono/Sunshine Kids for use with this restraint is not allowed. Use of such products voids manufacturer’s warranty and may seriously impact the products ability to perform properly in an accident.

Dorel (Cosco, Eddie Bauer, Maxi Cosi, Safety 1st)

Dorel Juvenile Group does not recommend the use of any child restraint accessories except those recommended by DJG.


In cold weather, DO NOT dress the child in bulky clothing like snowsuits if the child is riding in a child restraint. Bulky coats/ snowsuits make it difficult to properly tighten the harness to the child, which may allow the child to be ejected from the restraint during a crash.


DO NOT use accessories or parts other than those provided by Graco. Their use could alter the performance of the car seat.


Never use clothing or blankets that interfere with providing a properly tightened harness. An unsecured child can come out of the restraint during a crash. Place blankets over child AFTER harness has been properly tightened.


Do not modify your Infant Car Seat or Base. Only use products and accessories approved by Orbit Baby to ensure the safety of your child. This limited warranty does not apply to: defects resulting from use with covers, inserts, accessories, tightening devices, or other components not supplied by or expressly approved in writing by Orbit Baby.

Peg Perego

Use only approved parts. Use of unapproved parts can affect the safety of the car seat and cause serious injuries in an accident.


When it is cold and you are using the seat in the Harness Mode, Recaro recommends the following tips to reduce possible injury or discomfort to your child:

Remove the child’s bulky clothing before restraining the child in the seat. This will help belts and other safety features function properly.
After restraining the child in the seat, cover the child and the restraint system with a blanket or their jacket to maintain warmth and comfort of the child.

TOMY/The First Years

DO NOT modify or attach any toys, padding, or other items to this seat. Untested modifications or padding could result in injury in a crash.


DO NOT secure an infant in the carrier with extra material, bulky clothing, or extra padding. Instead, place a blanket over the harness after properly securing the child.

35 Responses to “Keep Kids WARM AND SAFE in the Car Seat”

  1. Anonymous says:

    >There is a great product called the Flip Over me Poncho. It was designed for children to wear in car seats so they don’t have to wear bulky jackets. It is a poncho that easily goes over child’s head. When they are placed in their car seat the back flips over the front so the child is comfortable and the harness can be tightened directly against their body. I have been using mine in the cold Chicago winter. I could not go through winter without it.

  2. Crystal says:

    >Great article! I personally have looked into the cruise cover (because it's so cute) but those Babbacovers are absolutely adorable. Thank you for pointing out the risks of using aftermarket products, as well as providing specific manufacture's warnings. I will be sharing this with friends.

  3. >Thanks for sharing about the Flip Over Me Poncho – it looks great and I have added it to the blog post as another safe alternative to the sleeping bags and bulky coats.

  4. kimbalaya says:

    >The Cozy Cover is a nice alternative also. It's similar to the infant carrier covers you already posted, but at about half the price.–Charcoal/dp/B004BNLIUS/ref=sr_1_10?s=baby-products&ie=UTF8&qid=1294367948&sr=1-10

  5. >Just in case anyone is thinking about trying it don't bother with the Cruise Cuddler also by SootheTime don't bother with it. It doesn't have the bulk like the bundle me. but it interferes with the straps, making it impossible to tighten as shown above. I do recommended their clip on blanket though. The clips are nice and strong, and it was easy to just unclip and wrap around my sweetie as we got out of the car. I also have a car seat poncho. I love it and get so many compliments!

  6. >Terrific article, as usual! The parachute analogy really hits the nail on the head. Thank you for featuring the Car Seat Poncho in your links and in the photo.

  7. Marianne says:

    >Great post. I love that you posted excerpts of all the manuals. I will definitely be pointing anyone with questionable car seat usage your way.

  8. Carolyn says:

    >off to cut my bundle me right now! Thanks for the video

  9. […] winter, dress your baby in thin tight layers and place a blanket or one of these car seat covers on top of her. Don’t put the baby in a snowsuit. You’ll avoid the baby overheating in […]

  10. Marshae Sun says:

    This is the best article I have yet read on the subject. A clear explaination of why it is an issue, and how to tell if something is a problem. It does not however include the one bit of information on this subject that I have been trying to find for 3-4 years now. When does it end? Do you stop worrying about fluff when they go to forward facing? (I’m guessing not.) When they switch to a regular seat belt? (Probably this since I’ve yet to see an example where the kid was in a regular seatbelt.) Once they are no longer in a booster? Should I be taking off my coat when I get in the car? (If so it seems I’d have heard that before now.) Maybe it’s an age or a height/weight they have to reach? Does anyone have an answer?

    • Marshae – great question! The honest truth is that everyone should eliminate the fluff under their harness/seat belt. For adults riding in the front seat of cars equipped with seat belt pretensioners, the severity of the problem is lessened. A pretensioner does exactly like what it sounds like it would do – it applies tension to the seat belt before something bad happens – specifically in the earliest split seconds of the crash it tightens your seat belt for you. Pretensioners are typically not found in the back seat – so adults riding in back, and kids in boosters in the back seat, won’t have access to pretensioners. When I ride in a car I either take my coat off completely, or unzip it so that I can pull it out from under the lap belt & shoulder belt (yes, it is still behind my back – but I typically wear a thinner coat.

  11. Amanda says:

    What are your thoughts on 7am Enfant’s Coocoon and Nido carseat warmers?

  12. Press says:

    What if you strap the kid in with the coat on but kept the straps the same as when there was no coat?

    • This is typically impossible to do. If you have made your straps properly snug, it is often impossible without the coat to take the child in/out without loosening and then retightening the straps.

  13. Kim says:

    It is currently 8 degrees Fahrenheit outside. I do not have a cozy garage in which to load my 16 month old twins. The threat of frostbite will become very real very soon and I find the suggestions for fiddling with coats once one gets to the car absolutely frustrating. The children are too small to help turn jackets around- it is a battle to get coats on in the first place. Thin fleece jackets are not warm enough (kiddos are chilly by the time we get to daycare), and blankets are quickly tossed on the ground before I get to the car, or thrown off once they are in their seats. You post leaves me to believe there not a better suggestion than ‘use a complicated time consuming product’ or ‘use a thin fleece jacket.’ If that is true, what is an option for not ideal in a crash but better for ease of use when inserting two toddlers who protest being strapped down?

    • The Cozywoggle may be the best option for your needs.

    • Angie says:

      Another option is to warm the car up before loading the kids. It’s cold here, too, and we don’t have a warm garage either. We put on thin coats with hats and mittens. And move quickly from the house to the car. Once in the car we either use puffy coats backwards or blankets. When it is extra cold, we put puffy coats on backwards to go from the house to the car. Layering of clothes is another great and safe way to keep them warmer.

    • Kate says:

      Hi, we live in Northern Canada and have the same issue. When they’re still rearfacing (for mine, that’s until they outgrow a Radian RF), we do thermal underwear top and bottom, long-sleeved shirt, thick fleece pants, hat, mittens, and patagonia down jacket. I keep fleece blankets in the car and usually cover each child with 2 of them, on top of snug harness. For my new forward-facer, pretty much the same thing, except when it’s really cold, she’s able to have the much thicker coat covering her over the harness (and blankets on her legs if she wants). The problem we run into, is them getting too hot once we’re into a heated building at the destination, but we put up with it.

    • Katie Marie says:

      I live in Minneapolis—Lots of cold here too. Most moms don’t take the time to take jackets off either. I will say I know it is pain— I know battling with that age blows… BUT now that i know the reasoning behind it… i have to do it.

      we buy Patagonia:

      We unzip and buckle them…rezip.. she has a picture with taht same jacket in her information above. These jackets are insanely warm. We call them their car seat jackets. They wear them in the car–not to play in the snow.

      good luck! Cold with car seats and babies is brutal.

    • Shannon says:

      I would recommend a fleece poncho ontop of their regular layered clothes and fleece jacket or fleece one piece suit. A 2 layer poncho will add enough warmth without adding the fuss of taking off their jacket and putting it back on. It’s also easier to put on in the house than a regular jacket and unlike a blanket they can’t drop it in the snow or in the car.

  14. Aisha says:

    What are your thoughts on the 7am enfant blanket 212? Would it be safe to use with a car seat?

    • The 212 Blanket is NOT safe for a car seat as there is a layer that goes under the baby’s body. The 212 Blanket is great in a stroller (we use it for our own kids in strollers as it is super warm).

  15. Megan Cassidy says:

    Thank you for the great information. Wondering why the good needs to come of the 7am pookie poncho? It seems to fit snuggly over the seat.
    Thank you!

  16. Kati A says:

    Where did you get the blue mittens pictured in the first kiddo pic in this post? Thanks!

  17. Elaine says:

    CuddleBabe seems like another good choice. It has an oval hole and is put on after baby is strapped in.

    • The CuddleBabe is safe but the fleece used is so thin that it doesn’t really do much to keep the baby warm – you are still going to need additional blankets on top of the baby for warmth.

  18. Natalie Justice says:

    Is this one safe since it goes over the car seat?

  19. Rachel says:

    Hello… my daughter is now 7 months old and I live in Canada where we get -30C in the winter with high wind since I live on a hill. I don’t have a garage and the driveway is far from the door. My own hands get cold while trying to attach the baby in the car, even if I wear leather gloves.

    I have now bought 5 winter suits for my daughter and 2 car seat covers. The car seat covers are no good now since she moved on to a convertible seat… she is a tall girl. I had 3 fleece/snowsuit that she outgrew. Now she has a thick fleece bunting suit (Gagou Tagou) and a warmer 2 piece/waterproof snow suit that I will have to use for the stroller only I guess.

    I tried the pinch test with the fleece suit and there is a small difference, especially around the legs.

    So today, since it was mild anyway, I tried using just a thin fleece jacket and some blankets. Well first off, her shoes fell off on the way to the car, and she pulled her shoes and her socks off during the drive. The blanket was also kicked away. When I got home, I checked her legs and feet and they were cold. This is just too frustrating!

    As a single mom, the struggle to get everything together to go anywhere with a baby is already hard. I also cannot go out to start the car in advance… leaving the baby alone in the house.

    I decided I’ll use the fleece suit but unzip the front part when in the car seat so at least the chest area is tighter, not much I can do about the legs though.

    • It sounds like you are doing a great job of trying to keep her safe. The larger size of the 7am Enfant Nido may work for her (don’t get the all fleece version, get the one that is shiny on the outside and fleece on the inside). You may also want to try the Cozywoggle coat.

  20. Shannon says:

    I have been sharing this article with all my friends with babies. Another friend had someone recommend the Rain or Shine Kids (RoSK) Pouch to me to use on the car seat and the front carrier. The lining is so soft and I am looking forward to using it over the carrier on snowy/rainy winter days while walking my elementary schooler to her school. Might you add this product under the carrier cover category with the Pookie Poncho and the Jolly Jumper?

    I have an Urban Bundle Me that i used with #1 that I will put on our stroller since I didn’t want to cut it. Thank you for this article and your updates as new products are added to the market!

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