A baby’s room should be kept between 68°F and 72°F (20°C to 22°C) for safe, comfortable sleep. This range sits in the sweet spot recommended by pediatric guidelines, warm enough to keep an infant comfortable without extra blankets but cool enough to avoid overheating, which is a known risk factor for Sudden Infant Death Syndrome (SIDS).
Why Temperature Matters for Safe Sleep
Infants are far less capable of regulating their own body temperature than adults. Their small bodies gain and lose heat quickly, and they can’t kick off covers or adjust clothing when they get too warm. This makes the room itself one of the most important variables in safe sleep.
Overheating has been linked to SIDS for decades, and a large national study of more than 60,000 SIDS cases confirmed the connection. During summer months, a 10°F increase in daily temperature was associated with an 8.6% rise in SIDS risk. The risk was even higher for certain groups: Black infants aged 3 to 11 months faced a 24.3% increased risk per 10°F temperature jump in summer. These numbers reinforce why keeping the nursery cool is not just about comfort.
Prone sleeping, overwrapping, and elevated room temperature all challenge an infant’s ability to shed heat. A cooler room with good air circulation works in the opposite direction, helping your baby maintain a stable temperature throughout the night.
The Recommended Range in Detail
Most pediatric organizations land in a similar zone. The NHS groups room temperatures into three tiers based on sleepwear ratings:
- 61°F to 69°F (16°C to 20°C): Standard room temperatures suitable for year-round sleep with a warmer sleep sack (2.5 tog)
- 69°F to 75°F (20°C to 24°C): Warmer rooms that call for a lighter sleep sack (1.0 tog)
- 75°F to 80°F (24°C to 27°C): Hot weather range where only a very thin layer (0.5 tog) is appropriate
The 68°F to 72°F target works well because it falls in the middle of these tiers, comfortable for most babies with a single layer of sleepwear and a standard sleep sack. If your home runs cooler or warmer, you can still keep your baby safe by adjusting what they wear to bed.
How to Dress Your Baby for the Room Temperature
Room temperature and sleepwear work as a pair. A 70°F room with a heavy blanket is more dangerous than a 65°F room with appropriate layering, because loose blankets pose suffocation risks and heavy wrapping traps heat. Sleep sacks (wearable blankets) solve both problems by providing warmth without loose fabric.
Tog ratings measure thermal resistance, essentially how much warmth a sleep sack provides. Here’s a practical breakdown:
- 3.5 tog: For cold rooms, roughly 53°F to 65°F. Pair with a long-sleeved onesie underneath.
- 2.5 tog: For cool to standard rooms, 59°F to 69°F. A regular onesie or footed sleeper underneath works well.
- 1.0 tog: For mild rooms, 67°F to 75°F. A short-sleeved bodysuit is usually enough underneath.
- 0.2 to 0.5 tog: For warm rooms above 75°F. Your baby may only need a diaper underneath.
The general rule: dress your baby in one more layer than you’d wear comfortably in the same room. If you’re fine in a t-shirt, your baby likely needs a onesie plus a light sleep sack.
How to Tell if Your Baby Is Too Hot or Too Cold
A room thermometer takes the guesswork out of monitoring, but your baby’s body gives you real-time feedback. The best place to check is the back of the neck or the chest. These core areas tell you more about true body temperature than hands or feet, which tend to feel cool in infants even when they’re perfectly warm.
Signs your baby is overheating include:
- Skin that feels hot to the touch on the chest or back of the neck
- Flushed or red skin, especially on the face
- Damp hair or sweating (though babies can overheat without visible sweating)
- Rapid breathing or an elevated heart rate
- Unusual fussiness, or the opposite: seeming unusually sluggish or limp
If your baby feels too cold, their chest will feel cool rather than warm. Cold hands alone aren’t a reliable signal. Add a layer or raise the thermostat slightly, then check again in 15 to 20 minutes.
Using Fans, Heaters, and Air Conditioning Safely
Air circulation in the nursery does more than keep things comfortable. A study published in JAMA Pediatrics found that using a fan during infant sleep was associated with a 72% reduction in SIDS risk. Fans help disperse exhaled carbon dioxide and prevent pockets of stale, warm air from forming around your baby’s face. A ceiling fan on low or a small room fan pointed away from the crib both work.
If you use air conditioning, set it to maintain a steady temperature rather than cycling between extremes. Avoid placing the crib directly beneath a vent or in the path of cold airflow. The same applies to heating: if you need a space heater in colder months, keep it well away from the crib and direct the warm air away from your baby. Space heaters also pose fire and burn risks, so never leave one running unattended in the nursery.
Humidity plays a supporting role too. Boston Children’s Hospital recommends keeping indoor humidity between 35% and 50%. Air that’s too dry can irritate your baby’s airways and skin, while air that’s too humid encourages mold growth. A simple hygrometer (often built into nursery thermometers) lets you monitor both temperature and humidity at a glance.
Seasonal Adjustments
Summer and winter each present their own challenges. In hot weather, the priority is preventing overheating. Use lighter sleepwear, run a fan, and consider air conditioning if your home regularly climbs above 75°F. On very hot nights, a diaper with a thin muslin sleep sack may be all your baby needs.
In winter, the instinct is to bundle up, but overbundling is one of the most common causes of infant overheating. Keep the thermostat at 68°F to 72°F overnight and use a warmer sleep sack rather than adding blankets, which should never be in the crib with a baby under 12 months. If your baby’s room is consistently colder than 65°F, a 2.5 or 3.5 tog sleep sack with a footed sleeper underneath provides plenty of warmth without loose bedding.
No matter the season, check your baby during the night if you’re unsure. A quick touch on the chest or back of the neck takes seconds and tells you whether you need to adjust layers or the thermostat.