The ideal nursery temperature is between 68°F and 72°F (20°C to 22°C) for most families, though the Lullaby Trust, a leading infant safety organization, recommends a slightly cooler range of 61°F to 68°F (16°C to 20°C). The key principle is simple: a room that feels comfortably cool to you is generally right for your baby. Keeping the nursery within this range reduces the risk of overheating, which is a known risk factor for Sudden Infant Death Syndrome (SIDS).
Why Overheating Is a Real Risk
Newborns and young infants can’t regulate their body temperature the way adults can. Their thermoregulatory system is still developing, which means they’re more vulnerable to heat stress during sleep. When an infant gets too warm, it can impair their ability to wake up, disrupt normal breathing patterns, and affect how well oxygen reaches the brain. These aren’t hypothetical concerns. A large national study of over 60,000 SIDS cases found that exposure to increased ambient temperature, even on just the same or previous day, was associated with higher SIDS risk during summer months.
Several well-known SIDS risk factors tie back to heat: sleeping face-down, being overdressed, bedroom heating, and bed-sharing all increase thermal stress on an infant. On the flip side, well-ventilated bedrooms and the use of a fan have been associated with a decreased risk. This is why temperature management in the nursery matters so much, especially during the first year of life.
How to Dress Your Baby for the Room Temperature
The room temperature alone doesn’t tell the whole story. What your baby wears to bed matters just as much. Sleep sacks (wearable blankets) are rated by a unit called TOG, which measures thermal resistance. The higher the TOG number, the warmer the sleep sack. Here’s a practical guide:
- 71°F and above (22°C+): A 0.2 or 0.3 TOG sleep sack, or just a short-sleeve onesie. This is the lightest option.
- 67°F to 75°F (19°C to 24°C): A 1.0 TOG sleep sack works well for this mild range.
- 59°F to 69°F (15°C to 21°C): A 2.5 TOG sleep sack provides more warmth for cooler rooms.
- 53°F to 65°F (12°C to 18°C): A 3.5 TOG sleep sack is the warmest option, suited for cold rooms in winter.
You’ll notice these ranges overlap, which gives you flexibility. If the nursery sits at 68°F, you could choose either the 1.0 or 2.5 TOG depending on whether your baby tends to run warm or cool. As a general rule, dress your baby in one layer more than what you’d find comfortable. Loose blankets are not recommended for infants under 12 months due to suffocation risk, which makes sleep sacks the safest bedding option.
Signs Your Baby Is Too Hot or Too Cold
Even with a thermometer in the room, your baby’s body is the best guide. To check, place your hand on the skin of their chest, belly, or the back of their neck. If the skin feels hot or clammy compared to your own, your baby is likely too warm. Look for sweating around the neck, back, and underarms, damp hair near the scalp, flushed cheeks, or heat rash (small red bumps on the skin).
Cold hands and feet alone aren’t a reliable signal. Babies commonly have cool extremities because their circulation is still maturing, and it doesn’t necessarily mean they’re underdressed. The chest and torso are what you should check. If the skin there feels cool to the touch, adding a layer or a warmer sleep sack is reasonable.
Getting an Accurate Room Reading
A simple room thermometer or a baby monitor with a built-in temperature sensor will do the job. Place it near the crib at roughly the same height where your baby sleeps, but not inside the crib itself. Avoid placing it near windows, heating vents, or exterior walls, since those spots will give you a skewed reading. The temperature in the center of the room at crib level is what you’re after.
Keep in mind that nursery temperature can shift throughout the night. A room that feels comfortable at bedtime may warm up or cool down several degrees by early morning. If your home temperature fluctuates significantly, checking the reading at different times for a few nights will give you a clearer picture of what your baby actually experiences during sleep.
Managing Nursery Temperature in Summer
Hot weather creates the biggest challenge. If you have air conditioning, use it. Indoor temperatures below 79°F (26°C) are considered safe for most people, while temperatures above 88°F (31°C) for extended periods can become dangerous. You don’t need to make the room cold, just comfortably cool.
If you don’t have air conditioning, a fan can help with air circulation, but don’t point it directly at your baby, as this can cause dehydration. Position it so it moves air around the room without blowing on the crib. During heat waves, close windows and curtains during the hottest part of the day to trap cooler air inside. If the temperature drops at night and it’s safe to do so, open windows to let cooler air in. On days when your home stays dangerously hot, spending time in an air-conditioned public space like a library or community center is a practical option.
Dress your baby in the lightest clothing possible on hot nights. A single-layer cotton onesie or even just a diaper with the lightest-weight sleep sack is appropriate when the room is above 75°F.
Managing Nursery Temperature in Winter
Cold-weather management is more straightforward. Set your thermostat to keep the nursery between 65°F and 72°F at night. Resist the urge to crank the heat or pile on layers. Bedroom heating is itself associated with increased SIDS risk when it pushes the temperature too high. A warmer sleep sack (2.5 or 3.5 TOG) with a long-sleeve onesie underneath is a safer approach than extra blankets or a hot room.
Space heaters introduce additional risks, including fire, burns, and carbon monoxide (with fuel-burning models). If you must use one, keep it well away from the crib, never leave it running while you sleep, and choose one with an automatic shutoff feature.
Humidity Also Matters
The ideal relative humidity for a nursery is between 35% and 50%. Air that’s too dry can irritate your baby’s nasal passages and make breathing harder, while air that’s too humid encourages mold growth and can also cause respiratory discomfort. A simple hygrometer (often built into baby monitors or room thermometers) will tell you where you stand. In dry winter months, a cool-mist humidifier can bring levels up. In humid summers, air conditioning or a dehumidifier brings them down.