A room below 68°F (20°C) is generally considered too cold for a baby to sleep comfortably without extra layers, and anything below 61°F (16°C) poses a real risk of dropping your baby’s body temperature to unsafe levels. The ideal sleeping range for infants falls between 68°F and 72°F (20°C to 22°C), which is roughly what feels comfortable for a lightly clothed adult.
Why Cold Matters Less Than You Think
Parents often worry more about cold than they should. The bigger danger during sleep is actually overheating. The NIH has warned that over-bundling babies during cold months, with multiple layers of heavy clothing, thick blankets, and warm room temperatures, increases the risk of sudden infant death syndrome (SIDS). So while you don’t want your baby sleeping in a frigid room, the instinct to pile on blankets and crank the heat can create a more dangerous situation than a slightly cool room.
That said, babies lose body heat faster than adults. Their small bodies have a high surface-area-to-weight ratio, and newborns in particular can’t shiver effectively or regulate their own temperature well. The World Health Organization defines newborn hypothermia as a body temperature below 97.7°F (36.5°C), and for very small or premature infants, every degree of temperature drop significantly raises health risks.
The Temperature Ranges to Know
Here’s how to think about room temperature for your baby’s sleep:
- 68°F to 72°F (20°C to 22°C): The sweet spot. A single layer of sleepwear or a light sleep sack is usually enough.
- 61°F to 68°F (16°C to 20°C): Cool but manageable. Your baby needs warmer sleepwear or a thicker sleep sack (rated around 2.5 TOG).
- Below 61°F (16°C): Too cold for safe infant sleep without serious insulation. A heavy-weight sleep sack (3.5 TOG) with pajamas underneath is recommended, but at this point you should really be warming the room itself.
A simple indoor thermometer near the crib takes the guesswork out of this. Room temperatures can vary significantly from what your thermostat reads, especially in older homes or rooms far from the heating source.
How to Tell if Your Baby Is Too Cold
Cold hands and feet are normal in babies and don’t reliably tell you whether they’re too cold. Instead, feel the skin on your baby’s chest, stomach, or back. It should feel warm and dry, not cool or clammy.
Signs your baby has gotten too cold include pale or cool skin on the torso, unusually slow breathing, and shivering. Lethargy or unusual stillness can also signal that a baby’s core temperature has dropped. If you notice these signs, add a layer and warm your baby against your body while you address the room temperature.
Keeping the Room Warm Safely
Central heating is the safest option. Set the thermostat so the nursery stays in the 68°F to 72°F range overnight. If you rely on a space heater, keep it at least three feet from the crib and anything flammable, plug it directly into a wall outlet (never an extension cord), and place it on a flat, hard surface like a bare floor. The general safety recommendation is to turn space heaters off before you go to sleep, which makes them a poor long-term solution for overnight nursery heating.
Avoid placing the crib near windows, exterior walls, or drafts. Even in a room that reads 70°F at the thermostat, a spot near a single-pane window can be significantly colder.
What to Dress Your Baby In
Since loose blankets, pillows, and stuffed animals should stay out of the crib entirely (per the American Academy of Pediatrics), the right sleepwear is your main tool for managing cold. Sleep sacks, sometimes called wearable blankets, are the safest option. They come rated by TOG, a measure of thermal resistance. The higher the TOG number, the warmer the garment.
For a room at 68°F, a 1.0 TOG sleep sack over a onesie works for most babies. Drop the room to the low 60s and you’ll want a 2.5 TOG sack with long-sleeved pajamas underneath. Below 61°F calls for a 3.5 TOG sack, ideally with a bodysuit and pajamas layered beneath it. These are starting points. Some babies run warm, others cool, so check your baby’s chest temperature after 15 to 20 minutes and adjust from there.
A useful rule of thumb: dress your baby in one more layer than you’d wear to sleep comfortably in the same room. If you’d want a T-shirt and a light blanket, your baby likely needs a onesie plus a medium-weight sleep sack.
Newborns Need Extra Attention
The first few weeks of life are when temperature regulation is weakest. The WHO recommends keeping rooms for newborns at a minimum of 77°F (25°C) in clinical settings, which is warmer than the standard advice for older infants. At home, this means erring on the warmer side of the 68°F to 72°F range for a newborn, particularly if the baby was premature or small at birth. Premature and low-birth-weight babies lose heat faster and may need a warmer room or additional layers even when the temperature seems fine for a full-term infant.
Skin-to-skin contact is one of the most effective ways to warm a newborn quickly. If your baby feels cool during a nighttime feeding or diaper change, holding them against your bare chest for several minutes helps stabilize their temperature before placing them back in the crib.