When your baby is small, it can be tricky to know what their temperature needs to be. But with a few simple guidelines, you can make sure they are comfortable throughout the day and sleep well at night.

When it’s hot outside, babies can get overheated easily. That’s why it’s important to dress them in clothing that won’t overheat, and that is breathable and lightweight.

A baby’s skin can be extremely sensitive to heat, so use a lightweight cotton or muslin fabric for all of their clothing. You can also add a lightweight swaddle blanket or sleep sack to keep them extra warm.

If you’re worried your baby may be too hot, a ceiling or floor fan can help cool down their room. However, don’t keep the fan on them too long – this can cause a heat surge and increase their risk of SIDS.

Your baby’s ideal sleeping temperature should be between 68 and 72 degrees F, according to Rachel Mitchell, a certified pediatric sleep consultant and founder of My Sweet Sleeper. “Sleeping is more difficult for a baby when they’re overheated, and that can increase the risk of Sudden Infant Death Syndrome (SIDS),” she says.

It’s a good idea to have an indoor thermometer in the nursery to be sure your baby stays within their optimum sleep temperature range. If you need to check baby’s temperature, it’s best to do so while they’re awake and not during the middle of the night.

You can also read your baby’s cues to help determine if their sleeping environment is too hot or too cold. Do they seem more restless, fussy, or awake than usual? If so, it’s time to change the clothing.

If your baby is overheated, remove the layers of clothing they’re wearing and head inside to take a closer look at their condition. If you notice blistered and white or pale gray skin or signs of hypothermia, call your doctor immediately.

When the weather gets cold, you’ll want to dress your little one in clothes designed for the chillier temperatures. This includes a light sleeper onesie or bodysuit, a thin sleep sack, and some warmer footies.

On cooler nights, you can add a thicker fleece swaddle or sleep sack over the standard cotton pajamas. You can also use a one-piece bunting, which keeps baby warm without the bulk of a blanket.

When it’s too cold to put your baby in a coat or snowsuit, you can choose a wearable blanket like this one from Bonds Wondercool that is made with breathable material. It’s soft and incredibly warm, and is available in sizes from 12 months to 24 months.