The simplest rule for dressing a baby at any temperature: put them in one more layer than you’re comfortable wearing yourself. If you’d be fine in a t-shirt, your baby needs a t-shirt plus a light layer on top. This “plus one” guideline from pediatric hospitals works as a quick starting point, but the specifics matter, especially for sleep, extreme weather, and car seats.
Room Temperature and Sleep
The ideal nursery temperature falls between 68°F and 72°F. What your baby wears to bed depends on where your room lands in that range, and the easiest way to get it right is using TOG ratings. TOG stands for Thermal Overall Grade, a standardized measure of how warm a garment or sleep sack is. The lower the number, the lighter the fabric.
Here’s how TOG ratings map to room temperature:
- 0.2 TOG: Best for warm rooms, 75°F to 81°F. Think a single layer of lightweight cotton or muslin.
- 1.0 TOG: Best for typical room temperatures, 68°F to 75°F. A standard sleep sack over a short-sleeve bodysuit works well here.
- 2.5 TOG: Best for cooler rooms, 61°F to 68°F. A thicker, quilted sleep sack, potentially with a long-sleeve layer underneath.
These ranges give you a framework, but every baby runs a little warmer or cooler. The real test is touching your baby’s chest or the back of their neck. If the skin there feels hot, sweaty, or clammy, they’re overdressed. Cool hands and feet alone don’t mean your baby is cold. Babies naturally have cooler extremities because their circulatory systems are still maturing. The chest and neck are the reliable spots to check.
Why Overheating Is a Serious Risk
Overheating isn’t just uncomfortable for babies. It’s a known risk factor for SIDS. Research published through the National Institutes of Health found that a 10°F increase in daily temperature during summer was associated with an 8.6% increased risk of SIDS. That risk was even steeper for certain groups: Black infants between 3 and 11 months old faced a 24.3% increased risk per 10°F rise in summer temperatures.
The same body of research found that bedroom heating increases SIDS risk, while well-ventilated rooms and fan use are associated with lower risk. This is why keeping the nursery cool and dressing your baby in appropriate layers matters more than piling on blankets. Loose blankets shouldn’t be in the crib at all for babies under 12 months. A properly rated sleep sack replaces the blanket entirely.
Skip the Hat Indoors
Many parents put a knit cap on their newborn at home because the hospital sent them home with one. But a 2023 study of full-term healthy newborns found that hats had no measurable impact on thermoregulation. Babies without hats were no more likely to experience low body temperature than babies wearing them. At home, a hat can actually work against you by trapping heat. Babies release excess warmth through their heads, so covering it indoors makes overheating more likely.
Dressing for Hot Weather
When temperatures climb above 75°F, less is more. On very hot days, a diaper and a sleeveless onesie may be all your baby needs. Stick with lightweight, breathable fabrics. Cotton is the classic choice, but bamboo viscose has gained popularity for good reason. Bamboo fibers are naturally porous and about 40% more absorbent than organic cotton, meaning they wick sweat away from the skin faster and allow better air circulation. Either fabric works well in the heat. Avoid polyester and synthetic blends, which trap warmth against the body.
Babies younger than 6 months should stay out of direct sunlight. Their skin is too thin and sensitive for prolonged sun exposure, and sunscreen isn’t recommended before 6 months. Lightweight long sleeves, a wide-brimmed hat, and shade are the best protection outdoors.
Dressing for Cold Weather
In cold weather, thin layers work better than one bulky piece. Layers trap warm air between them and let you adjust easily when you move between outdoors and a heated car or store. A good cold-weather setup for a baby might look like a bodysuit base layer, a fleece or knit middle layer, and a weather-appropriate outer layer.
One critical safety note for winter: puffy coats and car seats don’t mix. The National Highway Traffic Safety Administration warns that bulky coats create extra room under the harness straps, leading to a dangerously loose fit in a crash. Instead, dress your baby in lightweight fleece layers that allow the harness to sit snug against their body. Once they’re buckled in, you can drape a blanket over the straps or put a coat on backwards over the properly fitted harness for warmth.
When Your Baby Has a Fever
It’s instinctive to bundle up a baby who has the chills, but this is one of the most common mistakes parents make during a fever. Overdressing a child with a fever can actually drive the temperature higher. The guidance from MedlinePlus is straightforward: one layer of lightweight clothing and one lightweight blanket for sleep. That’s it.
Don’t add extra blankets even if your baby seems cold or is shivering. Shivering is the body’s attempt to generate heat, and piling on layers reinforces the cycle. Cold baths and ice are also counterproductive because they trigger more shivering. A lightly dressed baby in a comfortable room gives the fever the best chance to come down on its own or with appropriate medication.
Quick Temperature-to-Clothing Guide
- Above 80°F: Diaper only, or diaper plus a sleeveless onesie. No socks needed.
- 75°F to 80°F: Single layer of lightweight cotton or bamboo. A short-sleeve bodysuit works.
- 68°F to 75°F: Bodysuit plus a light sleep sack (1.0 TOG) for sleep, or bodysuit plus a light layer for daytime.
- 61°F to 68°F: Long-sleeve bodysuit plus a warmer sleep sack (2.5 TOG) for sleep. Add socks or footed pajamas.
- Below 61°F: Multiple thin layers. Long-sleeve bodysuit, footed pajamas or pants with socks, and a 2.5+ TOG sleep sack for sleep. Outdoors, add a hat and mittens.
How to Tell If You Got It Right
Check your baby’s chest, back, or neck about 10 minutes after putting them down or heading outside. Skin that feels warm and dry means you nailed it. Sweating, flushed skin, or damp hair at the nape of the neck means they’re too warm. Remove a layer. Skin that feels cool to the touch on the torso (not just the hands) means they need another layer. Heat rash, which looks like tiny red bumps, is another sign of overdressing. It typically shows up around the neck, back, and underarms.
Newborns need slightly more attention to layering than older infants because they can’t regulate their body temperature as efficiently. By about 3 months, most babies have better thermoregulation, though they still need that extra layer compared to adults. As your baby starts crawling and moving more, their activity generates additional body heat, so you may find yourself dressing them in fewer layers than you did in the newborn stage.