The right temperature for your baby’s room

In Germany, the guidance on nursery temperature is refreshingly clear. The medical guideline on preventing sudden infant death syndrome (updated 2022) and public health authorities recommend 64 °F (18 °C) as the ideal nighttime room temperature. Pediatricians’ associations suggest 61 to 64 °F (16 to 18 °C). If your thermometer shows somewhere in that range at night, you’re right on track.

Look beyond one country’s advice, though, and the picture gets more varied. The NHS in the UK recommends about 61–68 °F (16–20 °C) and advises keeping an eye on the temperature with a room thermometer. The AAP in the U.S. doesn’t give a specific number at all, but instead offers a rule of thumb: your baby should wear no more than one layer more than you would need to feel comfortable in the same room. And an Australian organization that advises parents on safe baby sleep says this very plainly: there’s no evidence that any one specific room temperature prevents sudden infant death syndrome.

Is that a contradiction? Not really. On one point, everyone agrees: overheating should be avoided. The studies that show overheating as a risk factor just define “too warm” differently—and the AAP acknowledges that too. That’s why there isn’t one number that protects on its own. What matters is the combination of room temperature, clothing, sleep sack, and your individual baby. Room temperature is simply the part you can measure and control most easily.

For everyday life, that means aiming for around 64 °F (18 °C) at night. Anywhere between 61 and 68 °F (16 and 20 °C) can work well if clothing and sleep sack match the room. If it gets warmer, dress your baby more lightly. If it drops below 61 °F (16 °C), add a warmer layer or a thicker sleep sack—or turn the heat up a little. An extra blanket is never the answer.

A baby regulates body temperature differently than you do. Adults cool themselves by sweating. Babies and young children can’t do that to the same extent yet, pediatric health experts note. They mainly release excess heat through the head. If the body is wrapped in too many layers or the head is covered, heat builds up.

This is about more than comfort. Overheating is considered a risk factor for sudden infant death syndrome. The German guideline lists avoiding overheating among the recommendations backed by solid evidence. The AAP and the NHS also explicitly name overheating as a risk—caused by too much clothing, too much bedding, or a room that’s too warm.

What makes this tricky is that if a baby is too cold, they’ll usually let you know loudly. If they’re too warm, they’ll often just keep sleeping—this is how German public health authorities describe it. Warmth is the quiet problem. That applies only to mild coolness, though: if a baby is truly too cold, they can become quiet and lethargic—so calm is not automatically a good sign. A 2001 sleep lab study fits with this: healthy babies, usually around 11 weeks old, who slept at 82 °F (28 °C) were harder to wake with noise between 3:00 and 6:00 a.m. than babies sleeping at 75 °F (24 °C)—and even 75 °F (24 °C) is already well above the recommended 64 °F (18 °C). Experts suspect that reduced arousability is one of the ways risk factors like heat may have an effect. The ability to rouse from sleep is considered an important built-in protection.

Please don’t read that as a reason to panic, but as an explanation for why a few simple habits matter so much. Sudden infant death syndrome has become rare in Germany: between 1991 and 2020, the rate fell by 93 percent, from 1,285 to 84 cases a year—mainly because parents avoid the known risk factors. And being too cold is clearly not the goal either. What you’re aiming for is a baby who feels warm, but not sweaty.

The thermometer tells you how warm the room is. Whether your baby is comfortable in it shows up in their skin—but only in the right place. Babies often have cool hands and feet even when they aren’t cold overall. That’s completely normal, and health experts broadly agree on that. The most reliable areas are the torso: the back of the neck, the chest, or the upper back between the shoulder blades. Guidelines commonly name the area between the shoulder blades when you’re unsure.

1. 1

   Warm your hand first: If your fingers are cold, rub your hands together briefly. With icy fingers, every baby feels warmer than they really are.

2. 2

   Check the right spot: Gently slide two fingers into the back of the neck or under the clothes at the upper back, between the shoulder blades. Most of the time, you can do this without waking your baby.

3. 3

   Read what you feel: Warm and dry is just right. Damp, sweaty, or truly hot means: too warm. Cool means: add a layer.

4. 4

   Change one thing at a time: Remove one layer or add one, switch to a lighter or warmer sleep sack—but only one change at a time—then feel again after a while.

The AAP lists other signs that your baby is too warm: sweating, damp hair, flushed cheeks or skin, and a hot chest. If small, raised, itchy bumps appear after warm days, it could be heat rash. It happens when your baby sweats a lot and sweat glands get blocked. The NHS explains that babies get it often because they can’t regulate their temperature as well as adults yet. For you, it’s a sign to dress your baby more lightly. To tell the difference, press a drinking glass firmly against the spots: if they don’t fade under the glass, it’s not heat rash—call 911 (or your local emergency number) right away, especially if your baby has a fever or seems unwell.

And what if your baby is too cold? If the neck feels cool, add one thin layer or switch to a warmer sleep sack. A blanket on top, by contrast, could slip over your baby’s face. Still, you should know the signs of true hypothermia: your baby feels cold on the body, seems limp, unusually quiet and sleepy, and doesn’t want to drink. This is an emergency—call 911 right away. Until help arrives, place your baby skin-to-skin on your bare chest wearing only a diaper, and cover both of you, keeping your baby’s face clear. Do not put a hot water bottle or heating pad directly on your baby’s skin.

A baby sleep sack solves two problems at once: it can’t slip over your baby’s head, and your baby can’t kick it off during the night. That’s why the AAP recommends it instead of a loose blanket. Pillows, sheepskins, crib bumpers, padded liners, and large stuffed animals don’t belong in a baby’s crib either—even as a source of warmth.

When you’re buying one, it’s worth looking closely at a few details:

• Neck opening: no larger than your baby’s head, so your baby can’t slip down into the sleep sack.

• Arm openings: snug enough that your baby can’t slide down into the sleep sack, but still roomy enough for free arm movement.

• No hood: The head stays uncovered.

• Length: body length minus head length, plus 4 to 6 in. (10 to 15 cm) for kicking room, say German health authorities. If the maker sizes by weight, follow that chart.

• Width: not too wide, so the fabric can’t wrap around your baby.

• No weights: The AAP explicitly advises against weighted sleep sacks, blankets, and swaddle sacks.

• Standard: In Europe, look for a note that the product meets the safety standard for baby sleep sacks, EN 16781. It covers things like the size of the neck and arm openings, small parts, cords, and how warmth is labeled. Wherever you buy, check these points yourself.

How warm a sleep sack is is shown by the TOG rating on the label. TOG is a measure of thermal insulation: the higher the number, the warmer it is. In stores, you’ll usually see values from 0.5 for airy summer sleep sacks to 3.5 for padded winter ones. Sleep sacks made to the European standard must list the rating and include guidance on which warmth level suits which conditions at home.

There isn’t, however, one independent chart that works for every sleep sack. The UK’s Lullaby Trust, which focuses on preventing sudden infant death syndrome, deliberately avoids publishing one: fabrics, fillings, and the warm air trapped between clothing layers affect warmth too much, and every baby is different. If you compare different manufacturers’ charts, their cutoffs can indeed be several degrees apart. But the overall pattern is similar—the overview below summarizes it.

Take these values as a starting point, not as law. What matters most is the chart for your own sleep sack and, in the end, your baby’s neck. In practice, two warmth levels are often enough: one light sleep sack for warm months and one medium-weight one for the rest of the year, combined with an extra clothing layer when needed.

If you don’t want to use a sleep sack, some guidelines describe an alternative: place your baby in bed so their feet touch the foot of the crib. That way, they can’t slide down with their head under the blanket. Use a light blanket and tuck it in securely. Never add a blanket on top of a sleep sack.

Under a sleep sack, babies usually need less than many people think. A diaper, bodysuit, and pajamas are usually enough—and in summer, even less may be plenty. Several thin cotton layers are more practical than one thick piece: you can easily remove one or add one. Just remember that warm air collects between layers. So every extra layer warms more than it looks like it would.

Manufacturer charts usually pair the sleep sack weights above with clothing like this:

• From about 75 °F (24 °C): 0.5 TOG, or just a sleeveless or short-sleeved bodysuit.

• About 68–75 °F (20–24 °C): about 1 TOG, with a short- or long-sleeved bodysuit underneath.

• About 61–68 °F (16–20 °C): about 2–2.5 TOG, with a long-sleeved bodysuit and, if needed, pajamas.

• Below about 61 °F (16 °C): 3–3.5 TOG with a bodysuit and pajamas — or turn the heat up a little.

Always go by your own sleep sack’s chart first, then do the neck check.

In practice, it might look like this:

• Winter night at 63 °F (17 °C): long-sleeved bodysuit, pajamas, and a sleep sack around 2.5 TOG. Cool feet are normal here and not a reason for an extra blanket.

• Mild night at 70 °F (21 °C): a bodysuit and a sleep sack around 1 TOG—or your all-season sleep sack with just a short-sleeved bodysuit underneath, as long as the neck stays dry.

• Hot night at 79 °F (26 °C): diaper and a sleeveless or short-sleeved bodysuit, plus at most a very thin summer sleep sack. On truly hot nights, a short-sleeved bodysuit or even just a diaper is okay, says the Lullaby Trust.

If you’re unsure, the AAP’s rule of thumb helps: think about what you yourself would wear in that room to feel comfortable—not counting your own blanket—and give your baby no more than one extra layer. The sleep sack counts as a layer too.

If you swaddle your baby, the swaddle blanket counts as its own layer. Your baby needs less underneath it accordingly, because according to the AAP, swaddling can increase the risk of a baby getting too warm. The legs should stay loosely bent and able to move at the hips: legs that are straightened and wrapped tightly can lead to hip problems. Safe-sleep guidance advises against tightly wrapping babies for sleep. If you do swaddle, use a thin fabric such as muslin or cotton, always place your baby on their back, and stop as soon as your baby shows the first signs of trying to roll—this is what the AAP and Australian safe-sleep experts recommend.

After the first birthday, the core rules stay the same. Many toddlers wriggle around at night and kick off every blanket—a sleep sack keeps warmth more even. For children who already stand and walk, there are styles with leg openings. For children from about age two, a thin blanket or a cotton sheet is usually enough on hot nights.

Because your baby mainly releases excess heat through the head, an uncovered head matters so much. A hat in bed, a hood on a sleep sack, or a cloth over the face blocks exactly that route. That’s why German health authorities advise never putting a hat on a baby at home and especially not in bed. The AAP says the same: once you’re home from the hospital, no hat indoors.

That also applies when you’re out and about. The NHS advises taking off hats and extra clothing as soon as you come in from the cold into a room, car, bus, or train—even if it wakes your baby. That can be hard when your baby has finally fallen asleep in the stroller. But in a warm store or a crowded train, heat builds quickly under a hat and stroller bunting. Often, taking the hat off and opening the bunting wide is enough.

At night, keep anything that could cover the head away from your baby: no blanket, no cloth, no burp cloth near the head of the crib. The AAP places avoiding overheating and head covering in its highest evidence category—meaning these are among the best-supported rules for safe baby sleep.

Your own sense of how warm a room feels is a poor guide. You’re moving around, wearing different clothes, or you may have just come from the warm kitchen. A simple room thermometer takes the guesswork out. Many baby monitors also show the temperature, and combo devices may measure humidity too.

Here’s how to get a reliable reading:

• At about the level where your baby lies—warm air rises, so it’s often warmer near the ceiling than at mattress height. Place the device next to the crib, for example on a dresser—never in the crib or attached to the rails, and keep any device with a cord at least 3.3 ft (1 m) away from the crib, because cords are a strangulation hazard.

• Not on a cold outside wall or by the window; there it will read too low.

• Not next to a heating vent or radiator, above electrical devices, or in the sun; there it will read too high.

• In the room where your baby actually sleeps. Since your baby should sleep in their own bed in the parents’ bedroom, the temperature there is what counts—not the nursery next door.

Check the thermometer in the evening before bedtime and, if you’re awake anyway, once in the second half of the night. Rooms often cool down noticeably overnight, especially if the heat is turned down. In summer it’s the opposite: a top-floor room may hold the day’s heat until late at night. After a few nights, you’ll know your room’s pattern and won’t need to keep checking constantly.

For crib placement, the rule is: not right next to a heating vent or radiator, not in direct sun, and positioned so no draft—from a window, fan, or air conditioner—blows over your baby’s head. German health authorities also advise airing out the room regularly for a few minutes with the window wide open. German environmental health authorities recommend airing each room for about five minutes two to three times a day in the cold season, and the bedroom for five to ten minutes in the morning after getting up. If you air it out briskly again just before bedtime, the air stays fresh without the room getting too cold. Your baby is best in another room while you do this.

Also remember: for bathing and diaper changes, the room can be much warmer because your baby is undressed. German health authorities recommend at least 73 °F (23 °C) for the bathroom. The 64 °F (18 °C) guideline is for sleep—when your baby is snug in a sleep sack.

If you live somewhere with cold winters, it’s tempting to make the bedroom really cozy and warm. Your baby usually doesn’t need that. The Lullaby Trust says it’s rarely necessary to run the heat all night—an extra clothing layer usually helps more. If you do keep the heat on, keep it low and do not let the room go above 68 °F (20 °C). German environmental health authorities recommend around 63 °F (17 °C) for a bedroom anyway. That fits well with the guidance for babies and also saves on heating bills.

If the room still gets too cool, for example in an older, poorly insulated home, the right fix is one thin extra layer under the sleep sack or a warmer sleep sack. What doesn’t belong in the crib is a blanket on top, a hot-water bottle, or a heating pad. If the room stays well below 61 °F (16 °C) even with the heat on, it’s worth looking at the cause: in cool rooms, moisture settles more easily on cold outside walls, and that’s where mold likes to grow.

Alongside temperature, humidity shapes the feel of a room. German environmental health authorities recommend a relative humidity between 40 and 60 percent indoors. In poorly insulated homes, it’s better to stay below 50 percent in winter so mold doesn’t form on cold walls. A simple hygrometer—often built right into a room thermometer—shows you where you stand.

If the reading stays well below 40 percent in winter, a humidifier can make sense. If you use one, a few points matter:

• No hot steam: The AAP recommends cool-mist humidifiers. Steam devices with hot water can cause scalds if a child gets too close or the unit tips over.

• Keep some distance: Place the unit about 3 ft (1 m) from the bed, with the cord out of reach.

• Keep it clean: Fill it with fresh water every day, empty the tank after each use, and let it dry. Clean it thoroughly about every 2–3 days of use, ideally using filtered or distilled water while it’s running.

• Don’t overdo it: A device that’s too large for a small room can cause moisture to condense on windows and walls—where bacteria and mold can grow.

• No fragrance oils: Essential oils such as eucalyptus oil, peppermint oil, and camphor can trigger life-threatening spasms of the larynx and even breathing to stop in babies and toddlers, even in tiny amounts and even as vapor. German risk-assessment experts advise avoiding fragrance diffusers and vaporizers around young children.

In summer, the question flips. German health authorities recommend keeping the temperature in sleep rooms from rising above 79 °F (26 °C) if possible, and advise letting your child sleep in the coolest room in the home. Because your baby should also sleep near you, that often means moving together on very hot nights—for example, to a north-facing room or one floor down. A travel crib makes that easy.

If temperatures barely drop below 77 °F (25 °C) even at night, children sometimes struggle to fall asleep and stay asleep, German health authorities note. So rougher nights during a heat wave aren’t a sign that you’re doing something wrong—they’re an understandable reaction to the heat.

Here’s how to keep as much heat out as possible:

• Close blinds, shades, or curtains during the day—ideally before the sun reaches the room.

• Air out the room when the air outside is cooler—at night and early in the morning.

• Use a fan to keep the air moving, but don’t aim it directly at your baby. It doesn’t lower the temperature, but the moving air feels cooler. Set it on a stable surface and out of reach.

• An air conditioner can cool the room—down to the same range you’d aim for otherwise, with clothing and sleep sack matched to the measured temperature. It shouldn’t blow directly onto the bed, because you want to avoid a draft on your baby’s head.

You may have read that a fan protects against sudden infant death syndrome. In fact, a California case-control study from 2008 found that babies who slept with a fan running were affected less often. But studies like that show an association, not proof. The AAP considers the evidence too thin to recommend fans as protection. Feel free to use one for cooling—the safe-sleep rules still matter just as much.

For sleeping in hot weather, a thin footless sleeper or a short-sleeved bodysuit is enough, and on very hot nights, just a diaper is okay too. A sleep sack is only an option then if it’s very light; for temperatures above 75 °F (24 °C), manufacturers usually recommend 0.5 TOG. A loose blanket is not a safe alternative, even in summer. If the thermometer climbs above 86 °F (30 °C), German public health authorities advise using damp cloths to help cool your baby—lukewarm to cool, never cold, and only while you’re right there: dab the neck, arms, and legs, but don’t place any cloth over your baby’s face or leave one in bed.

On hot days, pay especially close attention to drinking. In the first four to six months, your baby gets enough fluid from breast milk or formula. On hot days, nurse more often or offer the bottle more often. A helpful day-to-day clue is the diaper count: if there are clearly fewer wet diapers than usual, the urine is dark, or your baby seems limp, have them checked by a doctor.

When you’re out, never drape the stroller with a cloth, blanket, or other cover that traps air—underneath, it can get dangerously hot very quickly. A parasol or sunshade that still lets air circulate is better. And never leave your child alone in the car, not even for a few minutes. In hot weather, it is life-threatening.

New place, new climate—when you travel, the neck check is especially useful. A few things make it easier:

• Pack a thermometer: Hotel rooms and vacation rentals are often much warmer or cooler than home, and heating or air conditioning sometimes runs full blast.

• Bring two warmth levels: If you’re traveling to a different season or climate zone, pack one light and one medium-weight sleep sack—or your all-season sleep sack plus light clothing to layer.

• Keep unfamiliar beds safe: Even in a travel crib, use only the mattress that belongs with it—no extra padding, pillows, or blankets.

• Air conditioning on vacation: Don’t let it blow directly onto the bed, and set it so the room stays within your usual range. A hotel room that’s heavily overcooled is too cold for a baby in a thin summer bodysuit.

• At Grandma and Grandpa’s: If the home is well heated, ask whether you can turn the heat down in the guest room and dress your baby more lightly.

In the car in cold weather, thick winter coats and snowsuits do not belong under the straps of an infant car seat or child seat, because the harness needs to fit snugly against the body. Pediatricians advise opening the coat and pulling it out from under the harness, or covering your child with a prewarmed blanket over the straps after buckling them in. As soon as the car is warm, take off the hat and remove the blanket. On long drives, regular breaks help—you can take your baby out of the seat and use the chance to feel the back of the neck too.

In the stroller or baby carrier, babies get warm faster than you’d think as soon as you come into a heated room. In a carrier or sling, your own body heat warms them too. So check the back of the neck more often in those situations, especially indoors or in the sun, and take off a layer rather than leave one on too many.

Sometimes your baby feels burning hot after a nap in a warm room. The first question is: could it be the environment? Remove one layer, move your baby to a cooler room, and offer the breast or the bottle. According to the AAP, a raised temperature from overheating is usually only mild and returns to normal within a few hours once the child is in a cooler place. But if your baby is under 3 months old, don’t wait to see: after undressing your baby, take a rectal temperature and act on the number as described below. If your baby seems lethargic or is feeding poorly, get medical help right away without waiting to measure.

Only a thermometer can tell you whether it’s actually a fever. In babies, the most accurate method is rectal. Readings under the arm or on the forehead can be noticeably lower—so a normal forehead reading is not reassuring in a baby under 3 months who feels hot: in that case, check rectally. German public health authorities define 99.7–101.1 °F (37.6–38.4 °C) as an elevated temperature and 101.3 °F (38.5 °C) and above as fever, or from 100.4 °F (38.0 °C) in the first weeks of life. The AAP and many children’s hospitals use 100.4 °F (38.0 °C) rectally as the cutoff across the board. More important than the definition is what you do:

In the first 3 months of life, your baby needs immediate medical care at 100.4 °F (38.0 °C) or higher rectally—at the very first reading, and even at night. In this age group, below 97.7 °F (36.5 °C) is also a warning sign: warm your baby skin-to-skin right away and have them seen urgently as well; if your baby seems lethargic, cold, or is feeding poorly, call 911. Between 3 and 6 months, UK guidance (NHS) treats 102.2 °F (39.0 °C) or higher as a reason to get immediate medical help, even if your baby seems alert. From about 6 months on, the height of the fever alone says little about how sick a child is. At that point, behavior, drinking, and warning signs matter more than the number itself.

Don’t bundle up a baby with a fever. It’s a common reflex, but babies overheat more easily than older children. That’s why the AAP explicitly warns against dressing or wrapping a feverish baby too warmly. Clothing and the sleep sack should still match the room temperature. If your baby has chills while the fever is rising, one thin extra layer is okay—but as soon as your baby feels hot or starts sweating, take it off again.

Helpful for the conversation at your pediatrician’s office: write down the time, the temperature, and how you measured it, because numbers from different methods can’t be compared directly. In Moonsleep, you can log the temperature together with the measurement method—so your partner or Grandma in the Care Team can immediately see when it was last checked and what the result was.

If your partner, grandparents, or a babysitter puts your baby down, it helps to stay on the same page. These five points fit on a note on the fridge:

1. 1

   Aim for 64 °F (18 °C) at night—anywhere from 61 to 68 °F (16 to 20 °C) can work with the right clothing.

2. 2

   Feel the neck or upper back, not the hands and feet: warm and dry is right.

3. 3

   Keep the head uncovered: no hat, no hood, nothing over the face.

4. 4

   Use a sleep sack instead of a blanket, no pillows, sheepskins, or bumpers—and always place your baby on their back.

5. 5

   When in doubt, go with one layer less rather than one too many, then check again after a while.

And for you: you do not need to monitor every half-degree every night. After a few weeks, you’ll know your room, your sleep sacks, and your baby. Then a quick glance at the thermometer at bedtime and a brief neck check when you’re looking in on them are usually enough.