As a pediatrician and parent, I am especially mindful of heat safety as children return to school and student athletes head back to practices, conditioning and games. Here on the Peninsula, late-summer and early-fall heat waves can still bring very hot conditions, even as the days begin to feel more like fall. A cooler morning or the fact that the calendar says “fall” does not necessarily mean conditions are safe for strenuous outdoor activity.
Kids can be remarkably resilient, but intense exercise in hot or humid conditions can overwhelm the body’s ability to cool itself. The good news is that most heat-related illness is preventable when families, coaches, schools and athletes plan ahead.
Know when the heat is a problem
Don’t rely on the thermometer alone. Humidity, direct sunlight and the playing surface all affect heat stress, which is why the heat index is more useful than temperature alone for sports decisions. A heat index of 90°F or higher warrants significant caution, while 105°F or higher is considered especially dangerous for children exercising outdoors. On those days, strenuous activity should be postponed, shortened or moved indoors.
There is no single number of minutes that is universally “safe” for exercise in the heat. Instead, the hotter and more humid it is, the shorter and less intense the activity should be. Practices should include frequent breaks in shade or air conditioning, and children should not be expected to push through symptoms. Particularly early in the season, athletes should gradually increase their exposure to heat over 7–14 days rather than jumping immediately into full-length, high-intensity practices.
Hydration is essential
Encourage children to drink throughout the day rather than waiting until they are thirsty. During vigorous exercise, children ages 9–12 generally need about 3–8 ounces of water every 20 minutes. Teen athletes may need approximately 34–50 ounces per hour, depending on their size, sweat rate and the environmental conditions.
For exercise lasting more than an hour or involving heavy sweating, an electrolyte-containing beverage may be appropriate.
Athletes should begin practice well hydrated, have fluids readily available throughout the session, and replace fluids afterward. Light-yellow urine is a useful everyday sign of adequate hydration.
Listen to your child
Not just the coach or the schedule. Headache, dizziness, nausea, unusual fatigue, muscle cramps, weakness or confusion are warning signs. The child should immediately stop exercising and move to a cool place. Confusion, loss of consciousness, seizures or a very high body temperature can indicate heat stroke, which is a medical emergency.
The goal isn’t to keep children out of the heat. It’s to make sure they can play, practice and compete safely. As the school year gets underway, keep an eye on those late-summer and early-fall Peninsula heat waves, and remember: the calendar may say fall, but the heat can still be very real!
Read Also: The Balanced Green Plate: A Family Guide to Vegetarian Nutrition
Jackie Phillips, MD, August 2026
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