The ideal room temperature for a baby is between 68 and 72°F (20 to 22°C). This range keeps infants comfortable during sleep without raising the risk of overheating, which is a known factor in sudden infant death syndrome (SIDS). Getting the room temperature right matters more than most parents realize, and it’s one of the simplest things you can control in your baby’s sleep environment.
Why Overheating Is Dangerous for Infants
Babies can’t regulate their body temperature the way adults can. Their thermoregulatory system is still developing, which means they’re far more vulnerable to heat stress. When the surrounding air is too warm, it can impair a baby’s ability to wake up from sleep, disrupt normal breathing patterns, and interfere with the reflexes that protect the airway. These are the same mechanisms involved in SIDS.
A large study analyzing over 60,000 SIDS cases in the United States found that for every 10°F increase in daily temperature during summer, the risk of SIDS rose by about 8.6%. The effect was especially pronounced in babies between 3 and 11 months old, who saw a nearly 17% increase in risk per 10°F rise. Black infants were disproportionately affected, with more than five times the heat-related SIDS risk compared to White infants for the same temperature increase, likely reflecting differences in access to air conditioning and cooler living environments.
Several well-known SIDS risk factors tie directly back to heat: placing a baby to sleep on their stomach traps warmth against the body, overdressing or overwrapping prevents heat from escaping, and a warm room compounds both problems. Keeping the nursery in that 68 to 72°F range removes one variable from the equation.
How to Check if Your Baby Is Too Warm or Too Cold
A room thermometer is the easiest way to monitor the nursery, but your baby’s body gives clear signals too. Touch the skin on their chest, back, or the back of their neck. It should feel warm but not hot or sweaty. If you notice dampness around the neck, back, or underarms, or if their skin feels noticeably hotter than yours, they’re too warm. Heat rash, small red bumps on the skin, is another sign of overheating.
Cool hands and feet are normal in babies and don’t necessarily mean they’re cold. The chest and torso are more reliable indicators. If the chest feels cool to the touch and the baby seems fussy or unsettled, add a layer rather than turning up the heat.
Dressing Your Baby for the Room Temperature
Sleep sacks (wearable blankets) are the safest option for keeping babies warm at night, since loose blankets pose a suffocation risk. Sleep sacks are rated by TOG, a measure of thermal resistance. The higher the TOG number, the warmer the garment. Here’s a general guide:
- 0.2 to 0.3 TOG: Best for rooms above 71°F. A single lightweight layer underneath.
- 1.0 TOG: Suited to 67 to 75°F. A light bodysuit or onesie underneath.
- 2.5 TOG: For cooler rooms between 59 and 69°F. A long-sleeve bodysuit underneath.
- 3.5 TOG: For cold rooms between 53 and 65°F. Warmer pajamas underneath.
A good rule of thumb: dress your baby in one more layer than you’d wear comfortably in the same room. Skip hats indoors, since babies release a lot of excess heat through their heads, and a hat can cause them to overheat even when the room feels fine.
Keeping the Nursery Cool in Summer
If you have central air conditioning, setting it to 68 to 72°F at night is the simplest solution. But many families don’t have AC or rely on window units that struggle during heat waves. In that case, a ceiling fan or a box fan can help circulate air and bring the temperature down. Position the fan so it moves air around the room rather than blowing directly on the baby.
Other strategies that help: close curtains or blinds during the afternoon to block direct sun, open windows on opposite sides of the home in the evening to create a cross breeze, and dress the baby in just a diaper with a thin 0.2 TOG sleep sack if the room is still above 75°F. During extreme heat events, many cities open public cooling centers, which can be a lifeline for families without adequate cooling at home.
Keeping the Nursery Warm in Winter
Cold rooms carry less risk than hot ones, but you still want your baby to sleep comfortably. If your home drops below 65°F at night, a higher-TOG sleep sack with a warm layer underneath will usually do the job. Space heaters can be hazardous in a nursery due to fire risk and the potential for localized overheating. If you use one, keep it well away from the crib and any fabric, and turn it off before you go to sleep.
Avoid piling on blankets, quilts, or stuffed animals in the crib. The crib should have nothing in it except a firm, fitted sheet. This applies for the entire first year.
Humidity Matters Too
Temperature is only part of the picture. The ideal humidity for a baby’s room is between 35 and 50%. When humidity drops below that range, the dry air can cause nosebleeds, irritated skin, and difficulty breathing. When it climbs above 50%, moisture encourages the growth of dust mites, mold, and other allergens that can trigger coughing and worsen asthma.
A simple hygrometer (often built into nursery thermometers) will tell you where you stand. In dry winter months, a cool-mist humidifier can bring levels up. In humid summers, running the air conditioner or a dehumidifier keeps moisture in check. Sudden swings in humidity can also irritate a baby’s airways, so aim for consistency rather than correcting only when things feel extreme.