The ideal room temperature for a baby is between 68°F and 72°F (20°C to 22°C). This range keeps your baby comfortable during sleep and awake time while reducing the risk of overheating, which is a known risk factor for Sudden Infant Death Syndrome (SIDS).
Why Babies Need a Narrower Temperature Range
Adults can adjust to a wide range of room temperatures without much trouble, but babies are far less efficient at regulating their own body heat. Infants have a higher surface area relative to their body mass, thinner skin, less insulating body fat, and limited ability to control blood flow to their extremities. They also can’t kick off a blanket, tell you they’re uncomfortable, or shiver effectively to warm up.
This means your baby’s body temperature rises and falls more easily with the surrounding environment. A room that feels perfectly fine to you might be too warm or too cool for an infant, especially during sleep when you’re not actively monitoring them.
The Link Between Overheating and SIDS
Overheating during sleep increases a baby’s risk of SIDS. The Mayo Clinic lists being too warm while sleeping as a contributing risk factor. The exact mechanism isn’t fully understood, but overheating appears to deepen sleep in ways that may interfere with a baby’s ability to rouse when something goes wrong, like a breathing obstruction.
One practical step beyond temperature control: using a fan in the nursery. A study found that running a fan in a baby’s room lowered SIDS risk by 72%, likely because circulating air reduces the chance of a baby rebreathing trapped carbon dioxide near their face. Fans don’t cool the air itself, so they won’t chill your baby. Even when a baby was already sleeping on their back, fan use was associated with a 16% reduction in SIDS risk.
Signs Your Baby Is Too Hot
The most reliable way to check is to feel the skin on your baby’s chest or the back of their neck. These areas reflect core body temperature better than hands or feet, which tend to run cool in infants regardless of room temperature. If the chest feels hot or clammy, your baby is likely overdressed or the room is too warm.
Other signs of overheating include:
- Flushed or red skin
- Sweating or damp hair (though babies can overheat without sweating)
- Fussiness or restlessness during sleep
- Rapid breathing or elevated heart rate
- Unusual sluggishness or listlessness
If your baby shows several of these signs, remove a layer of clothing, adjust the thermostat, or move them to a cooler area of the house.
Signs Your Baby Is Too Cold
A room that dips well below 68°F can also be a problem. Cold babies tend to be fussy, have cool torsos (not just cold hands and feet), and may become less active or feed poorly. In more serious cases, the CDC notes that babies with hypothermia develop bright red, cold skin and very low energy. Cold stress forces an infant’s body to burn more calories to generate heat, which can be especially risky for newborns and preterm babies.
Cold hands and feet alone aren’t cause for concern. Babies have immature circulation, so their extremities often feel cooler than the rest of their body. The chest and belly are the areas to check.
What to Dress Your Baby In for Sleep
Room temperature and clothing work together. A sleep sack (wearable blanket) is the safest alternative to loose blankets, which are not recommended in a crib. Sleep sacks come with TOG ratings that indicate their thermal resistance, and matching the right TOG to your room temperature keeps your baby comfortable without overheating.
Here’s a general guide:
- 75°F to 81°F: A lightweight 0.2 TOG sleep sack, or just a onesie
- 68°F to 75°F: A 1.0 TOG sleep sack over a short-sleeved bodysuit
- 64°F to 72°F: A 1.5 TOG sleep sack with pajamas underneath
- 61°F to 68°F: A 2.5 TOG sleep sack with long-sleeved pajamas and a bodysuit
- Below 61°F: A 3.5 TOG sleep sack with warm layers underneath
These are starting points, not rules. Every baby runs a little warmer or cooler. Check your baby’s chest about 20 minutes after putting them down to see if the combination is working. Adjust from there. The key principle is to layer clothing rather than adding blankets, hats, or extra bedding to the crib. Never cover your baby’s head during sleep, as the head is a major source of heat release.
Keeping the Nursery at the Right Temperature
A simple room thermometer placed near the crib gives you a reliable reading. Your own comfort isn’t always a good proxy, since adults often prefer rooms warmer than 72°F, especially in winter. If you’re comfortable in a t-shirt, the room is probably in the right range for a baby in a sleep sack.
In summer, air conditioning or a fan can keep the room from climbing too high. In winter, avoid placing the crib near radiators, heating vents, or sunny windows, which can create hot spots even when the rest of the room is at the right temperature. Direct sunlight through a window can raise the temperature around the crib by several degrees without changing what the thermostat reads.
The 68°F to 72°F range applies year-round. Seasonal changes in humidity can affect how warm a room feels, so a thermometer is more reliable than your own perception. If your home doesn’t have central air and temperatures spike above 75°F, a fan pointed away from the crib (to circulate air without creating a direct breeze) helps keep conditions safe.