A baby’s room should be kept between 68°F and 72°F (20°C to 22°C) for safe, comfortable sleep. UK health guidelines recommend a slightly cooler range of 61°F to 68°F (16°C to 20°C) paired with appropriate sleepwear. The core principle across all guidelines is the same: a room that feels comfortable to a lightly dressed adult is about right for a baby.
Why Room Temperature Matters for Babies
Babies can’t regulate their body temperature the way adults can. They lose heat rapidly through their heads and skin, but they also overheat quickly because they can’t kick off blankets or adjust their clothing. Overheating during sleep increases the risk of Sudden Infant Death Syndrome (SIDS). The Mayo Clinic lists being too warm while sleeping as a direct risk factor.
The danger isn’t just discomfort. When a baby overheats, their arousal responses can be suppressed, meaning they’re less likely to wake up and reposition if their breathing becomes compromised. This is one reason safe sleep guidelines emphasize temperature control alongside back sleeping and a firm, bare mattress.
How to Tell If Your Baby Is Too Warm
A room thermometer gives you a number, but your baby’s body gives you the real answer. The most reliable spot to check is the back of the neck or the chest. If the skin there feels hot or sweaty, your baby is overdressed or the room is too warm. Hands and feet tend to run cool in newborns, so they’re not a reliable indicator.
Signs of overheating to watch for include:
- Flushed or red skin, especially on the face
- Damp hair or sweating (though babies can overheat without visibly sweating)
- Restlessness or fussiness that doesn’t have another obvious cause
- Rapid breathing or elevated heart rate
- Sluggishness or unusual tiredness
If your baby shows several of these signs, remove a layer of clothing, offer a feeding for hydration, and check the room temperature.
Choosing the Right Sleepwear by Temperature
Sleep sacks (wearable blankets) are rated using a TOG system, which measures thermal resistance. A higher TOG number means a warmer sleep sack. Matching the TOG to your room temperature keeps your baby comfortable without loose blankets in the crib.
- 75°F to 81°F (24°C to 27°C): 0.2 TOG, essentially a single muslin layer
- 68°F to 75°F (20°C to 24°C): 1.0 TOG, a light sleep sack
- 64°F to 72°F (18°C to 22°C): 1.5 TOG, a medium-weight sleep sack
- 61°F to 68°F (16°C to 20°C): 2.5 TOG, a warmer sleep sack
- Below 61°F (16°C): 3.5 TOG, the warmest option
Underneath the sleep sack, a short-sleeved bodysuit works for warmer rooms and a long-sleeved bodysuit or pajamas for cooler ones. Skip hats indoors. Babies release excess heat through their heads, and covering it interferes with that process.
Keeping the Nursery Consistent in Summer and Winter
Room temperature can swing significantly between day and night, especially during seasonal extremes. A digital thermometer in the nursery is the simplest way to catch those shifts. Place it near the crib at baby-height, not on a wall that gets direct sunlight or sits next to a vent.
In summer, the challenge is keeping the room cool enough. Thermal curtains or cellular shades block solar heat gain through windows, sometimes dropping room temperature several degrees on their own. If you use air conditioning, avoid pointing the airflow directly at the crib. A programmable thermostat set to maintain 68°F to 72°F overnight takes the guesswork out of temperature regulation.
In winter, the room can drop quickly if your heating cycles off. Programming your thermostat to hold a steady overnight temperature helps, and closing vents in unused rooms directs more warm air to the nursery. If you rely on a portable space heater as a backup, never leave it unattended in the baby’s room, and keep it well away from the crib and any fabric.
The Case for a Fan in the Nursery
A study published in the Archives of Pediatrics and Adolescent Medicine found that running a fan in a baby’s room lowered SIDS risk by 72 percent. The likely reason: moving air reduces “rebreathing,” where exhaled carbon dioxide pools near a baby’s face, particularly if they roll or shift during sleep. A fan doesn’t cool the air the way air conditioning does. It simply circulates it, so your baby won’t get chilled unless they’re already sweating.
The benefit was largest for babies in higher-risk sleep situations, and smaller (about 16 percent, though not statistically significant on its own) for babies already sleeping on their backs on a firm surface. A fan is an easy addition to an already safe sleep setup, not a replacement for it. Keep cords out of reach and make sure the fan is stable enough that a curious toddler or pet can’t knock it over.
Practical Setup for New Parents
You don’t need an elaborate monitoring system. A basic digital nursery thermometer costs under $15 and gives you a reliable reading. Check it before bedtime, and glance at it during nighttime feedings to see how the room temperature shifts overnight. Most parents find that once they dial in their thermostat settings and have two or three TOG options for different seasons, temperature management becomes second nature within the first few weeks.
If your home doesn’t have central air or heating, or if temperatures in your area swing dramatically, a smart thermometer that sends alerts to your phone when the room drifts outside a set range can offer peace of mind. These typically cost $20 to $40 and pair with a smartphone app. The goal isn’t perfection. Staying within a few degrees of that 68°F to 72°F window gives your baby a safe, comfortable sleep environment.