The ideal temperature for a newborn’s room is between 68 and 72°F (20 to 22°C). Keeping your home in this range helps your baby sleep safely and comfortably while reducing the risk of overheating, which is a known risk factor for Sudden Infant Death Syndrome (SIDS).
Why Temperature Matters for Newborns
Newborns can’t regulate their body temperature the way adults can. They lose heat quickly through exposed skin, but they also overheat easily because they can’t kick off blankets or tell you they’re uncomfortable. A room that feels perfectly fine to you might be too warm for a swaddled baby in a sleep sack.
Overheating increases the risk of SIDS. The NHS lists room temperature as a direct factor, recommending that babies never sleep near radiators, heaters, or in direct sunlight. The concern isn’t just discomfort. When a baby gets too warm during sleep, their arousal responses can be suppressed, making it harder for them to wake if their breathing is compromised.
How to Check if Your Baby Is Comfortable
A room thermometer is the simplest tool. Place it near the crib, away from windows and vents, to get an accurate reading of the air your baby actually breathes. But the thermometer only tells part of the story. Your baby’s body gives you the rest.
Feel your baby’s chest or the back of their neck. The skin there should be warm but not hot or sweaty. Don’t worry if their hands or feet feel cool, as that’s normal in newborns and doesn’t mean they’re cold. Signs your baby is too warm include flushed or red skin, sweating, damp hair, and general fussiness or restlessness. If you notice any of these, remove a layer of clothing or bedding and check again in a few minutes.
A newborn’s normal body temperature ranges from 96.8 to 99.5°F. Anything consistently above that, combined with visible signs of overheating, means the room or the clothing needs to change.
What Your Baby Should Wear to Sleep
The general rule: dress your baby in one layer more than what you’d wear to be comfortable in the same room. If you’re fine in a t-shirt, your baby probably needs a onesie plus a light sleep sack. If you need a sweater, your baby might need a warmer layer underneath their sleep sack.
Sleep sacks are rated by TOG, a measure of thermal resistance. A TOG rating of 1.0 works well for rooms between 68 and 75°F. If your home runs cooler, between 61 and 68°F, a 2.5 TOG sleep sack provides more insulation. Matching the right TOG to your room temperature takes the guesswork out of layering.
Swaddling is another option for the first few weeks. The American Academy of Pediatrics says babies can be swaddled for up to 12 to 20 hours per day early on, but you need to stop swaddling once your baby shows any signs of rolling over. After that point, a sleep sack with arms free is the safer choice.
Keeping the Room Cool in Summer
When outdoor temperatures climb, getting the nursery down to 72°F can be a challenge. Air conditioning is perfectly safe for newborns as long as the airflow isn’t blowing directly on the crib. Point vents away from the sleep area or use a deflector.
A fan in the room can also help. A study published in The Archives of Pediatrics and Adolescent Medicine compared 185 SIDS cases with 312 matched controls and found that simply having a fan running in the room lowered SIDS risk by 72 percent. The benefit was even larger for babies sleeping in warmer rooms. Researchers believe fans reduce the chance of a baby rebreathing trapped carbon dioxide near their face. A fan doesn’t replace putting your baby on their back or removing soft bedding, but it adds a meaningful layer of protection, especially on hot nights when hitting that 68 to 72°F target is difficult.
Keeping the Room Warm in Winter
Position the crib in the warmest, most consistent part of the room. Keep it away from drafty windows and heating vents, which can create hot and cold spots. Cotton or flannel fitted sheets retain heat better than standard materials, and a higher-TOG sleep sack handles the rest without loose blankets in the crib.
If you’re heading outside, layer your baby and add a hat and socks. But remove any bulky clothing before strapping your baby into a car seat. Puffy jackets create slack in the harness that can be dangerous in a crash. Once buckled in snugly, tuck a blanket over their lap for warmth.
During extreme cold or power outages, maintaining a safe temperature becomes urgent. If your heat goes out and you can’t restore it quickly, take your baby to a warming center or a friend’s home with working heat. Stock warm clothes, diapers, formula, and water ahead of any predicted winter storms. If you use a generator, run it outdoors and well away from any windows or doors.
Humidity Also Plays a Role
Temperature gets most of the attention, but humidity matters too. The ideal range for a nursery is 35 to 50 percent. Air that’s too dry can cause nosebleeds, dry skin, and irritated airways. Air that’s too humid encourages dust mites, mold, and allergens that make breathing harder for small lungs.
A simple hygrometer (often built into room thermometers sold for nurseries) tracks humidity alongside temperature. In dry winter months, a cool-mist humidifier can bring levels up. In sticky summers, your air conditioning typically handles dehumidification on its own. If it doesn’t, a standalone dehumidifier keeps things in range.
Quick Reference by Room Temperature
- 61 to 68°F: Long-sleeve onesie, 2.5 TOG sleep sack, socks. Consider flannel sheets.
- 68 to 72°F: Short or long-sleeve onesie, 1.0 TOG sleep sack. This is the target range.
- 72 to 75°F: Short-sleeve onesie or just a diaper with a lightweight 0.5 TOG sleep sack. Use a fan for air circulation.
- Above 75°F: A diaper alone may be enough. Run a fan, use air conditioning if available, and check for signs of overheating frequently.