What Is a Normal Baby Temperature?

As almost any parent will tell you, there is nothing more frightening than your baby's first fever. Yet, surprisingly it is a somewhat common occurrence with about 14 out of every 1,000 healthy infants developing a fever between 8 and 60 days old. For this reason, it can be helpful to know what the average temperature is for your baby—and what constitutes a fever—before that first elevated number makes its debut.

While you do not have to take your baby's temperature unless you feel it is warranted, it is important to know that your baby's temperature will fluctuate throughout the day, says Jean Siri Moorjani, MD, FAAP, a board-certified pediatrician with Arnold Palmer Hospital for Children at Orlando Health. So, even though this number may stray in one direction or another from the average temperature, this does not mean your baby is sick unless their temperature reaches 100.4.

Below we explore what an average temperature might be for your little one, the most reliable way to take your baby's temperature, and when the number on the thermometer warrants a call to your baby's pediatrician or healthcare provider.

How to Take Your Baby's Temperature

When it comes to taking your baby's temperature, there are a lot of options available. These include a rectal thermometer, a forehead (temporal) thermometer, an ear (tympanic) thermometer, and an armpit (axillary) thermometer, says Ali Alhassani, MD, FAAP, a board-certified pediatrician and head of clinical at Summer Health.

"Overall, the rectal thermometer is the most accurate, especially for newborns," Dr. Alhassani says. "Of course, it can also be the most uncomfortable. Tympanic thermometers are a great option for quick temperatures in older babies, although if there is a lot of ear wax or a curved ear canal, the reading can become compromised."

Because rectal thermometers tend to be the most accurate, your pediatrician will likely recommend that you start there, especially in newborns. To take your baby's temperature rectally, you will need to place them on their stomach and lubricate the metal tip of a rectal thermometer, suggests Dr. Moorjani. Then, carefully insert just the tip of the thermometer into your baby's bottom.

"A rectal temperature is most reliable since it is your baby's core temperature," Dr. Moorjani adds. "If you take your baby's temperature another way, be sure to tell your pediatrician which method you used. Also, a good rule of thumb is to add one degree to the temperature reading if you did not take their temperature rectally."

If taking your baby's temperature rectally makes you uneasy, you can start with a temporal thermometer at any age, or a tympanic thermometer at age 6 months, says Therese M. Linnon, DO, FAAP, a board-certified pediatrician with Akron Children's Hospital. But if their temperature is elevated, she advises taking their temperature again using a rectal thermometer, especially if your baby is younger than 12 months old.

Average Baby Temperature

It is important to know your baby's average temperature in order to keep them safe. Not only is your baby unable to communicate how they are feeling, but their immune system is not very strong at a young age, so taking their temperature is one way of identifying a potential issue, advises Dr. Moorjani.

"Generally, a reading of 98.6 degrees Fahrenheit (or 37 degrees Celsius) is the average rectal temperature," she says.

That said, a normal low for your baby might be a temperature of 96.8 degrees Fahrenheit in the morning. Then, it might move up to 100.3 degrees Fahrenheit later in the day. But, this type of fluctuation is completely normal.

In fact, your baby's body temperature is lowest in the middle of night and in the early morning, while it tends to be higher in the late afternoon and early evening. Additionally, infants generally tend to have higher temperatures than older children.

It is not until your baby's temperature reaches 100.4 degrees Fahrenheit that you need to be concerned—unless your baby is showing other signs of illness such as not eating well, sleeping more, or appearing irritable or lethargic, Dr. Moorjani says.

"Babies can also go in opposite direction and have really low temperatures when they are sick," she adds. "But that is more rare, thankfully."

Your baby's temperature also might fluctuate throughout the day because of environmental factors, says Christina Johns, MD, MEd, FAAP, pediatric emergency doctor and senior medical advisor at PM Pediatric Care. "Bundling or layering [your baby], outside temperatures, physical activity, and mild viral illnesses can all cause a baby's temperature to go up and down."

What if My Baby's Temperature Is Slightly High or Low?

As mentioned earlier, your baby's temperature can fluctuate throughout the day. Sometimes this variation is benign, and other times it can be caused by environmental factors.

"A slight change in a baby's temperature can be caused by various factors, including illness or infection, vaccination, overdressing or underdressing, room temperature, and weather," says Dr. Alhassani. "It is important to...consult a pediatrician if the temperature change is accompanied by other symptoms or if the change persists."

If your baby's temperature is within the normal range of 96.8 degrees Fahrenheit to 100.3 degrees Fahrenheit, you can try making changes at home to alleviate any symptoms. Here are some tips on how to handle slightly high or slightly low temperatures.

Tips for Slightly High Temperatures

If your baby's temperature is slightly high—meaning they are warm but do not have have a fever—you could try dressing your baby lightly and ensure that their room is a comfortable temperature, says Dr. Alhassani.

You also can offer them plenty of fluids. But you should avoid giving them any over-the-counter fever medication without a healthcare provider's advice. These medications are usually based on weight and some may not be appropriate for really young babies, he says.

"Consult a pediatrician for further advice, especially if your baby is showing other symptoms, such as lethargy, discomfort, or changes in feeding patterns," Dr. Alhassani says.

Tips for Slightly Low Temperatures

If your baby’s temperature is slightly low, but not below 96.8, you can try several things to help them warm up. For instance, you could try dressing them in one more layer than what you are wearing, suggests Dr. Moorjani.

In other words, if you are wearing a long-sleeve shirt inside, your baby might need a onesie and a long-sleeve shirt. But be careful not to over-bundle your baby, as they may cause them to overheat.

"If a baby's temperature is low, but within the normal range, make sure that their skin is dry, cover or wrap them in a blanket, provide skin-to-skin contact, and/or try feeding," suggests Dr. Johns.

It also is important to monitor your baby's temperature and contact a healthcare provider if the low temperature persists, Dr. Alhassani suggests. "Also, make sure you confirm a low temperature first with a rectal thermometer, as other methods can often give falsely low temperatures."

When to Contact Your Healthcare Provider

While you may instinctively want to bring your child to the pediatrician's office at the first sign of a temperature fluctuation, that may not be necessary if your baby's temp is within the normal range and they seem otherwise fine, Dr. Linnon says.

"True fever, which is defined as 100.4 or greater, is usually caused by a variety of infections; changes in temperature can also occur with overdressing or with being exposed to warmer environments," she says. "But, if your baby is 2 months old or younger with a rectal temperature of 100.4 degrees Fahrenheit or higher, you should contact your pediatrician immediately."

With young babies, there is a worry about serious bacterial infections like sepsis, Dr. Moorjani says. The best place to start is with a call to your baby's pediatrician or healthcare provider. But, if it is after hours and you cannot get in touch with them, you should take your baby to the nearest emergency room for evaluation, she says.

"Depending on the cause of the fever, a baby may need bloodwork or testing," she says. "In some cases, they may even be hospitalized for observation or get IV antibiotics until test results come back. Babies cannot tell us what is wrong, so we do testing to make sure they are not seriously ill. We also may treat them like they have a bacterial infection and start antibiotics until we get test results."

If your baby is not responsive or having difficulty breathing, then call 911, Dr. Johns says. "If your baby isn’t acting like themselves or if you are concerned, it’s always good to check in with your healthcare professional for guidance on next steps."

Also, it is important to remember that babies younger than 6 months should only have Tylenol and never ibuprofen, she adds. To get the correct dosage for your little one, call your child's pediatrician.

A Word From Verywell

The first time you notice an elevated temperature in your baby, you may feel a little overwhelmed and wonder what you should do next. The good news is that there are very clear guidelines on what constitutes a normal temperature in a baby and when you need to reach out to a healthcare provider.

As long as your baby's temperature stays between 96.8 degrees Fahrenheit and 100.3 degrees Fahrenheit, you likely have nothing to worry about. However, if your baby is under 2 months old and hits the 100.4 mark (or drops below 96.8), it is important that you call a healthcare provider right away or take them to the emergency room if it is after hours.

If your baby is older, a temperature of 100.4 may warrant a call to your child's pediatrician, but it is likely they will suggest home care for the fever unless they are experiencing other concerning symptoms like not eating, sleeping more than normal, displaying excessive irritability, or acting lethargic. In these situations, you need to have them evaluated right away.