Summer is upon us, and for kids, that means spending lots of time outdoors.

According to the Centers for Disease Control and Prevention, infants and children younger than four are among those at the greatest risk for heat-related illnesses.

Health experts say it's important to recognize that children and adults tolerate heat very differently. ?Children have thin skin and they don't manage the heat exchange well. They tend to lose more fluids through their skin and so they need extra fluids relative to what an adult does,? says Dr. James Fortenberry of the Children's Healthcare of Atlanta.

For babies under six months, doctors suggest keeping them out of direct sun and have them hydrated prior to going out, and drink every 20-30 minutes.

Older kids need to also drink before going out. In addition, they should take frequent breaks to rehydrate and avoid sodas with caffeine.

Parents should be able to recognize symptoms of heat illness which include faintness, extreme tiredness, nausea, fever, or muscle spasms.