There is no single thermostat setting proven safest or most comfortable for every sleeping baby. A useful starting point is a room that feels comfortable to a lightly clothed adult, with the baby dressed for that room and checked for signs of overheating. The American Academy of Pediatrics (AAP) focuses on avoiding overbundling rather than naming one universal temperature 12.
Some public-health organizations do give a practical range. The UK National Health Service advises 16°C to 20°C, or about 61°F to 68°F, for a baby's room. This is guidance for setting up the room, not a pass-or-fail medical threshold. Clothing, a sleep sack, direct sunlight, heating, air conditioning, and the baby's health all change how warm the baby actually feels 3.
Choose a starting temperature, then check the baby
Set the thermostat to a comfortable indoor temperature that your home can maintain safely. If you use the NHS range, treat it as a starting point rather than trying to hold the room at one exact degree. The AAP and Health Canada instead emphasize dressing the baby appropriately for the room and watching for overheating 12.
A simple room thermometer can make seasonal changes easier to see. Keep it outside the crib and out of the baby's reach, away from direct sun, a radiator, a heater, or an air-conditioning vent. Check it near bedtime and again when outdoor temperature or heating changes substantially. A monitor's temperature display can be useful, but the number does not replace checking the baby.
Feel the baby's chest, tummy, or the back of the neck:
- Warm and dry: The current clothing is probably comfortable.
- Hot, sweaty, damp, or flushed: Remove a layer and make the room more comfortable.
- Cool at the chest or back of the neck: Add one fitted layer and check again.
Hands and feet often feel cooler than the baby's core, so they are not a good reason by themselves to add more bedding. The NIH Safe to Sleep campaign lists sweating, flushed or hot skin, and a hot chest as signs that a baby may be too warm 45.
Dress for the room without overbundling
The AAP advises dressing an infant in no more than one layer more than an adult would wear to feel comfortable in the same environment. That is a ceiling, not a requirement to add an extra layer when the baby is already warm 1.
Use simple, fitted sleepwear. If more warmth is needed, a correctly sized, nonweighted wearable blanket or sleep sack can be used instead of a loose blanket. Make sure the neck and arm openings do not allow the baby to slip inside, and choose a product intended for the baby's current size and room conditions 2.
A TOG value describes a garment's thermal insulation, but it does not create one universal outfit chart. Materials, layers underneath, fit, and product construction vary. Follow the specific manufacturer's temperature and clothing instructions, then check the baby's chest or neck. Do not combine several products merely to reach a target TOG number.
Keep these boundaries clear:
- Do not use weighted sleep sacks, swaddles, sleepers, or blankets.
- Do not use outdoor clothing, such as a snowsuit or jacket, for indoor sleep.
- Do not place a hat on a sleeping baby indoors unless the baby's medical team has given a specific reason. Hospital use in the first hours after birth or in a neonatal unit does not make a hat routine home sleepwear.
- Do not add loose blankets, pillows, bumpers, toys, or positioning products for warmth.
These recommendations reduce overheating, suffocation, entrapment, and head-covering hazards 142.
If you swaddle, temperature is only one safety check
Swaddling is not a way to reduce SIDS risk. If you choose to swaddle, place the baby on the back, keep the material snug enough not to come loose but loose enough for breathing and hip movement, and never use a weighted swaddle. Stop as soon as the baby shows signs of trying to roll, which can happen earlier than many parents expect 1.
Count the swaddle as part of the baby's clothing. A warm room, pajamas, and a swaddle can add up to overbundling even when each item seems light on its own. An arms-free sleep sack that allows free movement is different from a product that compresses the chest and arms, but it still needs to fit correctly and suit the room 2.
Adjust safely in hot or cold weather
In hot weather
Use lighter fitted sleepwear and remove unnecessary layers. Close blinds or curtains before direct sun heats the room, and use air conditioning or a safely placed fan to circulate air when needed. Keep fan and appliance cords well away from the crib, and do not aim strong airflow directly at the baby 3.
A fan may help make a hot room more comfortable, but it should not be presented as protection against SIDS. The AAP found insufficient evidence to recommend a fan as a SIDS risk-reduction strategy 1.
Do not drape a blanket, damp cloth, or cover over the crib to block light or cool the space. It can obstruct airflow, fall into the sleep area, or contribute to overheating. Keep the baby's face and head uncovered 64.
In cold weather
Warm the room safely or add one fitted clothing layer. A well-fitting, nonweighted sleep sack is preferable to loose bedding. Never put a hot-water bottle in the baby's sleep space, and keep the crib away from radiators, fires, portable heaters, and other direct heat 7.
Recheck the baby's chest or neck rather than dressing only for the outdoor forecast. Indoor temperature can change as heating cycles, sunlight fades, or a door opens.
Temperature does not replace the rest of safe sleep
A comfortable room cannot make an unsafe sleep surface safe. For every nap and nighttime sleep:
- Place the baby on the back.
- Use a firm, flat, noninclined mattress in an approved crib, bassinet, or other infant sleep space.
- Use only a fitted sheet and keep the space free of pillows, blankets, toys, bumpers, nests, and positioners.
- Keep the baby's face and head uncovered.
These are core AAP and NIH safe-sleep recommendations. Our baby sleep guide covers the broader sleep pattern and routine questions; temperature is only one part of the sleep environment 146.
Normal warmth, fever, and heat illness are different
A warm chest or sweaty neck in an otherwise alert baby calls for fewer layers and a more comfortable room. It does not tell you whether the baby has a fever. If the baby feels unusually hot or seems unwell, use a digital thermometer and follow the measurement method recommended for the baby's age.
A rectal temperature of 100.4°F (38°C) or higher is considered a fever. For a baby age 3 months or younger, call the pediatrician immediately even if there are no other symptoms 8.
Seek emergency care now if a baby has trouble breathing, blue or gray lips or skin, a seizure, is unresponsive or very hard to wake, or may have heatstroke. Move the baby to a cooler place and remove excess outer layers while emergency help is on the way. Do not delay care while trying to correct the room temperature 89.
For an older infant, follow the pediatrician's guidance for the measured temperature and symptoms. Call promptly for poor feeding, repeated vomiting, fewer wet diapers, unusual sleepiness, or any concern that the baby is becoming ill. A room-temperature adjustment is not a substitute for assessing illness.
Premature or medically vulnerable babies need their own plan
General room guidance is written for infants at home without individualized temperature instructions. A baby born prematurely or at low birth weight, recently discharged from a neonatal unit, or living with an illness that affects temperature or fluid management may need a different plan.
Follow the neonatal or pediatric team's discharge instructions for the room, clothing, feeding, and temperature checks. Do not continue hospital warming practices, hats, or equipment at home unless that team specifically directs it 17.
