A newborn’s room should be kept between 68 and 72°F (20 to 22°C). Temperatures above 72°F may be too warm and can increase the risk of overheating, which is a known risk factor for Sudden Infant Death Syndrome (SIDS). Keeping the room comfortably cool, rather than warm, is the safer direction to err.
Why Temperature Matters for Newborns
Newborns can’t regulate their body temperature the way adults can. When a baby gets too cold, their body burns extra calories to generate heat through a process called chemical thermogenesis, which can increase their metabolic rate and oxygen consumption by two to three times the normal level. That’s energy diverted away from growth. Prolonged cold stress can also cause drops in blood sugar and other metabolic problems.
Overheating carries a different and more acute danger. Excess heat can interfere with a baby’s brain-based systems for controlling temperature and breathing. This is one of the mechanisms researchers believe links overheating to SIDS. The risk isn’t just from high room temperatures alone. Blankets, hats worn indoors, and too many layers of clothing all trap body heat and contribute to the problem.
How to Tell If Your Baby Is Too Hot or Too Cold
A room thermometer is helpful, but your baby’s body gives you the most reliable feedback. To check, touch the skin on their chest or the back of their neck. These areas reflect core temperature better than hands and feet, which tend to run cool in newborns regardless of how warm they are overall. A normal rectal temperature for a newborn falls between 97.7°F and 99.5°F.
Signs of overheating include:
- Skin that feels hot to the touch
- Flushed or red face
- Sweating or damp hair (though some babies overheat without sweating)
- Fussiness or restlessness
- Rapid heart rate
- Unusual sleepiness, limpness, or sluggishness
A baby who is too cold will feel cool on the chest or belly, not just on the hands and feet. They may become less active or feed poorly. Cold stress can actually begin before their core temperature drops measurably, so if the room feels chilly to you in light clothing, it’s likely too cold for your baby.
Dressing Your Baby for Sleep
The American Academy of Pediatrics doesn’t specify a single room temperature but advises dressing your baby appropriately for whatever the ambient temperature is. Sleep sacks and wearable blankets are the safest options because they keep your baby warm without the suffocation risk of loose bedding.
Sleep sacks are rated using a TOG system, which measures thermal resistance. Higher TOG numbers mean more warmth. Here’s how TOG ratings match up to room temperature:
- 0.2 TOG: 75°F to 81°F (very light, essentially a single layer of muslin)
- 1.0 TOG: 68°F to 75°F (the sweet spot for most climate-controlled homes)
- 1.5 TOG: 64°F to 72°F
- 2.5 TOG: 61°F to 68°F (cooler rooms, winter months)
- 3.5 TOG: Below 61°F
A good rule of thumb: dress your baby in one more layer than you’d be comfortable wearing in the same room. Skip hats indoors, as they trap a significant amount of heat. Loose blankets, pillows, bumper pads, and stuffed animals should stay out of the crib entirely.
Air Circulation and Humidity
A fan in the nursery does more than keep things cool. A study published in the Archives of Pediatrics and Adolescent Medicine found that having a fan running in a baby’s room lowered SIDS risk by 72 percent. The likely reason is that moving air prevents pockets of exhaled carbon dioxide from collecting around a baby’s face, which is one of the proposed contributors to SIDS. The fan doesn’t need to blow directly on the baby. A ceiling fan on low or a small fan pointed at a wall works fine.
Humidity also plays a role in comfort. Boston Children’s Hospital recommends keeping indoor humidity between 35 and 50 percent. Air that’s too dry can irritate your baby’s nasal passages and skin, leading to nosebleeds, dry skin, and difficulty breathing. Air that’s too humid encourages mold, dust mites, and allergens. A simple hygrometer (available for a few dollars at any hardware store) can help you monitor levels, and a humidifier or dehumidifier can adjust them as needed.
Setting Up the Room
Place the crib away from windows, exterior walls, heating vents, radiators, and direct sunlight. All of these create temperature inconsistencies that a room thermometer on the opposite wall won’t catch. If the crib is next to a drafty window in winter or a sun-facing wall in summer, the temperature your baby experiences could be several degrees different from what the thermostat reads.
A small digital thermometer placed near the crib at mattress height gives you the most accurate reading of what your baby is actually feeling. Check it at bedtime and again in the early morning hours, when temperatures tend to drop. Many baby monitors now include built-in temperature sensors that alert you if the room drifts outside a set range, which can be especially useful during seasonal transitions when nighttime temperatures are unpredictable.