A newborn’s room should be kept between 68 and 72°F (20 to 22°C). This range keeps babies comfortable without raising the risk of overheating, which is a known factor in sudden infant death syndrome (SIDS). The UK’s Lullaby Trust recommends a slightly wider range of 61 to 68°F (16 to 20°C), reflecting cooler indoor norms in British homes. Wherever you land within these ranges, the goal is the same: warm enough to prevent cold stress, cool enough to avoid overheating.
Why Temperature Matters So Much for Newborns
Newborns are surprisingly bad at regulating their own body temperature. They have a high surface area relative to their body weight, which means they lose heat quickly. At the same time, they can’t shiver effectively or reposition themselves to stay warm the way older children can. Their primary heat source is a special type of fat called brown fat, which burns calories to generate warmth, but this supply is limited, especially in babies born early or at a low birth weight.
When a baby gets too cold, their body diverts oxygen and energy toward producing heat. This increases demand on already limited glucose stores and can lower oxygen levels in the blood. According to the World Health Organization, hypothermia contributes to an estimated 40% of neonatal deaths globally, though much of that burden falls on low-resource settings without climate-controlled housing. For full-term, healthy babies in temperature-controlled homes, the risk is far lower, but it underscores why keeping the room warm matters.
Overheating carries its own danger. Being too warm during sleep increases a baby’s risk of SIDS. The exact mechanism isn’t fully understood, but the association is well established. This is why pediatric guidelines emphasize a ceiling on room temperature, not just a floor.
How to Check if Your Baby Is Too Hot or Cold
Don’t rely on your baby’s hands and feet to judge their temperature. It’s completely normal for a newborn’s fingers and toes to feel cool to the touch, even when the rest of their body is perfectly warm. Instead, place your hand on their chest or upper back. The skin there should feel warm and dry, not hot, clammy, or cool.
Signs your baby is too cold include pale skin, slow breathing, and unusually still or lethargic behavior. Shivering can happen but is less reliable in very young infants. Signs of overheating are more visible: flushed or red skin, sweating (particularly on the back of the neck), rapid breathing, and general restlessness or fussiness. If your baby’s chest feels hot and their skin looks red, remove a layer and recheck in 10 to 15 minutes.
Getting an Accurate Room Reading
A thermostat on the wall across the house won’t tell you much about the temperature where your baby actually sleeps. Place a simple room thermometer near the crib, at roughly the same height as the mattress. Avoid spots near windows, exterior walls, heating vents, or direct sunlight, all of which can skew the reading several degrees in either direction. Many baby monitors now include a built-in temperature sensor, which works well as long as the monitor is positioned close to the sleep area.
Check the reading at different times of day. Rooms often cool significantly after midnight, especially in homes where the thermostat is set to drop overnight. If you notice a swing of more than a few degrees between bedtime and early morning, adjusting your baby’s clothing layers is usually easier than reprogramming your heating system.
Dressing Your Baby for Sleep
The right sleepwear depends directly on room temperature. Sleep sacks (wearable blankets) are the safest option because they eliminate the suffocation risk that comes with loose blankets. These are rated using a TOG system, which measures thermal resistance. Here’s a general guide:
- 71°F and above (22°C+): A lightweight 0.2 or 0.3 TOG sleep sack, or just a onesie
- 67 to 75°F (19 to 24°C): A 1.0 TOG sleep sack over a short-sleeve bodysuit
- 59 to 69°F (15 to 21°C): A 2.5 TOG sleep sack over a long-sleeve bodysuit
- 53 to 65°F (12 to 18°C): A 3.5 TOG sleep sack with warmer layers underneath
These ranges overlap intentionally. A baby who runs warm might need a lighter TOG at the same room temperature as a baby who runs cool. Use the chest-check method to fine-tune. One consistent rule: never cover your baby’s head during sleep. Babies release a significant amount of excess heat through their heads, and covering it interferes with that cooling mechanism.
Managing Temperature in Summer and Winter
Summer heat is the harder challenge for most parents because it’s easier to add layers than to cool a room without air conditioning. If your home doesn’t have AC, a fan in the room can help. Gentle air circulation not only keeps the temperature more even but has also been associated with a reduced risk of SIDS. Point the fan toward a wall or the ceiling rather than directly at the crib, so the breeze doesn’t blow on your baby’s skin. On very hot nights, dress your baby in just a diaper and a thin cotton bodysuit, or skip the sleep sack entirely if the room is above 75°F.
In winter, the temptation is to pile on blankets. Resist it. Loose bedding in a crib is a suffocation hazard regardless of the temperature. A properly rated sleep sack and appropriate layers underneath are all your baby needs. If the room drops below 65°F overnight, a space heater can help, but choose one with an automatic shutoff and keep it well away from the crib, curtains, and any fabric. A humidifier can also make a cool room feel more comfortable, since dry heated air can irritate a baby’s nasal passages and make sleep harder.
Keep the crib away from drafty windows, exterior walls, and heating vents. Even in a room that reads 70°F at the thermometer, a spot directly under a vent or next to a single-pane window can be noticeably warmer or cooler.
Premature and Low Birth Weight Babies
Babies born early or weighing under about 5.5 pounds are more vulnerable to temperature swings. They have less brown fat for heat production, thinner skin, and even more surface area relative to their size. The WHO notes that for very small infants, the odds of serious complications rise roughly 28% for every 1°C (1.8°F) drop in body temperature. These babies often need the room kept at the warmer end of the recommended range, closer to 72°F, and may need an extra layer compared to a full-term infant at the same room temperature. If your baby was born prematurely, your pediatrician or neonatal team will typically give you specific guidance on home temperature before discharge.