Babies don't have the ability to sweat and cool their bodies as well as older children and adults, so take extra care in dressing your little one during hot days. Look for soft, cotton fabrics that won't trap moisture and will allow your baby's skin to breathe. Loose-fitting clothing, such as a bodysuit and elastic-band shorts or sundress, are ideal. Dress your child in light layers so you can shed these as the day gets warmer or if you are moving from sun to shade. Keep in mind that dark-colored clothing absorbs heat; dressing your baby in lighter colors will help her feel as cool as possible.
The pediatricians at the Sutter Health Network in Northern California recommend keeping your baby covered with long-sleeved, lightweight clothing, [and a] hat, and sunshades as needed when temperatures are under 80 degrees Fahrenheit. They add, "If the temperature is in the 80 to 90 degrees Fahrenheit range or above, all your baby needs is a diaper and a T-shirt, a hat, and shade." If your baby is overdressed, she may become sweaty and develop a heat rash. If your baby is underdressed, she'll have cool hands and feet and a cold back. You can tell if your baby is dressed just right if her hands and feet are cool to the touch and her body feels warm.