The ideal room temperature for a newborn is between 68 and 72 degrees Fahrenheit (20 to 22 degrees Celsius). This range keeps your baby comfortable without increasing the risk of overheating, which is a known risk factor for Sudden Infant Death Syndrome (SIDS).
Why This Temperature Range Matters
Newborns can’t regulate their body temperature the way adults can. When the room is too warm, a baby’s cardiovascular and respiratory systems are directly affected. Heat stress can slow heart rate, cause brief pauses in breathing, and reduce oxygen levels in the blood. Worse, overheating impairs a baby’s ability to wake up or self-correct when breathing becomes irregular during sleep.
Research published in Frontiers in Pediatrics found that heat stress and elevated body temperature are common findings in SIDS cases. Even small increases above a comfortable temperature range can shift a sleeping infant’s nervous system toward stress responses, reducing the natural protective reflexes that help babies recover from interrupted breathing during both REM and non-REM sleep. A combination of low oxygen and overheating is particularly dangerous: in animal studies, hypoxia alone or heat alone didn’t prevent recovery from breathing pauses, but the two together did.
How to Tell if Your Baby Is Too Hot or Too Cold
A room thermometer is the simplest way to monitor the nursery, but your baby’s body also gives clear signals. The best place to check is the chest, back of the neck, or tummy. If the skin there feels warm and dry, your baby is comfortable. If it feels damp or hot, your baby is overheating. Flushed skin and rapid breathing are also signs of too much heat.
One common mistake: checking your baby’s hands and feet. Newborns naturally have cool extremities because their circulatory system prioritizes blood flow to the core and vital organs. Cold fingers or toes don’t mean your baby needs another blanket. Focus on the torso and neck instead.
Dressing Your Baby for Sleep
The American Academy of Pediatrics recommends dressing your baby in one layer more than you’d wear comfortably in the same room. If you’re fine in a t-shirt, your baby likely needs a onesie plus a lightweight sleep sack.
Sleep sacks are rated using a TOG system (Thermal Overall Grade), which measures how much warmth they provide. Matching the right TOG to your room temperature keeps your baby in a safe zone:
- 75°F to 81°F: 0.2 TOG (very lightweight, essentially a single layer of muslin or cotton)
- 68°F to 75°F: 1.0 TOG (a standard lightweight sleep sack)
- 64°F to 72°F: 1.5 TOG (slightly warmer, good for cooler rooms)
- 61°F to 68°F: 2.5 TOG (a padded or quilted sleep sack)
- Below 61°F: 3.5 TOG (the warmest option, for cold environments)
Loose blankets are not recommended for infants under 12 months because of suffocation risk. A properly sized sleep sack replaces blankets entirely.
Air Circulation Makes a Difference
A fan running in the nursery during sleep was associated with a 72% reduction in SIDS risk in a study from the Archives of Pediatrics & Adolescent Medicine. The effect was strongest in warmer rooms, where fan use was linked to a 94% risk reduction compared to no fan. The benefit was also more pronounced when other risk factors were present, such as sleeping on the side or stomach.
A fan doesn’t need to blow directly on your baby. Gentle air circulation in the room helps prevent pockets of warm, stale air from forming around your baby’s face and head. This matters because the head is a major source of heat loss for infants. When warm air gets trapped around the face, the brain’s temperature-regulating center cools less effectively, compounding the risks of overheating.
Adjusting for Winter and Summer
In winter, keep the thermostat at or below 72°F and resist the urge to bundle your baby in extra layers. If your home runs cold and you use a space heater, place it well away from the crib and never leave it running unattended overnight. A room thermometer near the crib (but out of reach) gives you a reliable reading of the air your baby actually sleeps in, which can differ from what your thermostat says.
In summer, air conditioning set within the 68 to 72°F range is perfectly safe. If you don’t have air conditioning, a fan becomes even more important. On hot nights, dress your baby in just a diaper and a 0.2 TOG sleep sack, or even a single layer of lightweight cotton. Keeping curtains or blinds closed during the day helps prevent the nursery from absorbing heat.
Head Covering and Overheating
Once your baby is indoors, remove any hats or head coverings. Babies release a significant amount of body heat through their heads. When the head is fully covered during sleep, facial skin temperature rises, reducing the body’s ability to shed heat through convection and evaporation. This directly raises the temperature of brain structures responsible for controlling heart rate, breathing, and arousal. Keeping the head uncovered during sleep is one of the simplest ways to help your baby regulate temperature safely.